Key to xenobiotic carotenoids.

A listing of carotenoids with heteroatoms (X = F, Cl, Br, I, Si, N, S, Se, Fe) directly attached to the carotenoid carbon skeleton has been compiled. The 178 listed carotenoids with C, H, X atoms demonstrate that the classical division of carotenoids into hydrocarbon carotenoids (C, H) and xanthophylls (C, H, O) has become obsolete.

1. Introduction

The number of natural occurring carotenoids registered in the relevant books on the topic has increased continuously: 19 carotenoids in 1934, 67 in 1948, 273 in 1971, 563 in 1987, 750 in 2004 [1,2,3,4,5]. The importance of the Carotenoids Handbook is evident for all those working frequently or occasionally with carotenoids. However, the extensive compilation of natural occurring carotenoids has ignored the existence of the numerous xenobiotic carotenoids [6]. The impact of the Carotenoids Handbook is overwhelming insofar that carotenoids with atoms other than C,H,O are barely thinkable. Carotenoids are still classified in two groups: carotenes (polyenes containing C,H) and xanthophylls (polyenes with C,H,O), and the occurrence of carotenoids with other atoms was not contemplated by the existing nomenclature rules. In contrast, the Natural Product Reports dedicate a specific chapter to steroids with heteroelements, sulfur flavonoids and heteroatom-substituted carbohydrates have been reviewed. [7,8,9,10]. Admittedly, no hetero-carotenoids have been detected so far in Nature, but nonetheless, it is not incongruous to expect carotenoids from sea organisms to incorporate Cl (compounds 5Cl-8Cl in the list) [11]; the interactions between selenium and carotenoids support speculations about the existence of combination products [12,13,14]. After all, heterocarotenoids may not keep forever their status as xenobiotic compounds, though by then, xenophobia towards xenobiotic carotenoids may be encountered. In a historical review on the “Development of Carotenoid Chemistry 1922–1991” the first Br-, N- and S-carotenoids (4Br-9Br, 2N, 12S) were ignored [15]. When the author’s first manuscript on carotenoid thioketones (1S-3S) was rejected by the referees, the honorary co-author commented the rejection as the logical consequence of working with bizarre compounds. The syntheses of selenium carotenoids (1Se-7Se) were regarded by some of the author’s colleagues as a completely useless, ill-famed and ill-smelling occupation. Strangely enough, the summarizing speaker at the end of a carotenoid conference intentionally omitted to mention the author’s presentation on S, N and Se carotenoids. Fortunately, these narrow-minded discriminatory prejudices have now tended to cease; heterocarotenoids have found applications impossible to achieve with “normal” carotenoids, e.g., 2S, 15S, 3Se, 12N, 46N [16,17,18,19].

Despite the increasing interest in xenobiotic carotenoids, searching the databases for these compounds often results in zero hits. The unawareness of heterocarotenoids may perhaps be the reason for avoidable syntheses. The molecular wire carotenoid thiol 15S was prepared in several steps [16]. Carotenoid thione 2S, synthesized previously from a commercial carotenoid in a one-step synthesis, could probably have been more appropriate for the investigation [20]. Even an author sensitized to xenobiotic carotenoids witnessed ignorance; compounds 25N, 27N, 29N were not cited in a paper on carotenoid oxime hydrochlorides 19N-22N [21,22]. Unfamiliarity with heterocarotenoids is possibly the cause for further lack of mention, e.g., nitrile carotenoid 6N was patented in 1990 and published in 2011 without referring to previous work from 1988; thienyl carotenoid 3◉S, first reported in 1981, was not cited when the compound was resynthesized 20 years later (for an explanation of the designation 3S see Section 4: Nomenclature).

This thematic issue of Molecules on “Carotenoids” now offers the opportunity to compile a systematic listing of xenobiotic carotenoids. This inventory is a first attempt to take these carotenoids out of their obscurity.

2. Historical Remarks

Carotenoids became eye-catching in 1906 with the invention of chromatography by Tswett and got scientific consecration with the first determination of their molecular formula by Willstäter in 1907 [23,24]. During the period of structure determination the first nitrogen carotenoids were prepared as analytical derivatives (oxime, semicarbazone) [25,26]. Bromo and sulfur carotenoids were synthesized in 1958 and 1959 and chloro carotenoids in 1976 [27,28,29]. The synthesis of carotenoid amines was not successful until 1990 [30,31,32]. The most heterogenic carotenoids are probably iron carbonyl compounds 5Fe-7Fe. The common Greek-letter termed cyclic end groups are now increasingly being replaced by heterocycles.

3. Selection Criteria

Polyenes with a branched polyene chain >C20 capped with different cyclic or acyclic end groups and with heteroatoms covalently bound to the carbon carotenoid were considered. Thus, compounds with a heteroatom linked via oxygen to the carotenoid scaffold were omitted (e.g., phosphates). Adhering strictly to the isoprenoid nature of carotenoids would not allow including the interesting aza compound 37N [33]. This compound has been perceived as an azine of retinal, but is much more attractive when viewed as a diazapolyene. Various carotenoid derivatives prepared for analytical purposes (oximes, hydrazones amides etc.) are not mentioned [34,35], unless the derivative has also found an application extending characterization, e.g., canthaxanthin oxime was skipped, canthaxanthin oxime hydrochloride 21N as a surface active hydrophilic carotenoid was included [22]. Some carotenoids are drawn in the concise all-trans form, since the dimension of the actual cis-isomers would be too space demanding, e.g., 32N and 33N. The main concern of the recording, the heteroatom character of the compound, is not affected by this presentation.

In a departure from Molecules’ normal style, reference registration in the compound list follows the example of the handbooks excluding article title and search-irrelevant data on the length of a paper. The references for the individual compounds are not exhaustive. A reader interested in a particular compound should perform a structural search in a database to receive complete and updated citations.

There certainly exist more xenobiotic carotenoids than presented in the list. Many hetero-carotenoids, especially from the patent literature, are not recorded owing to search problems or involuntary neglect. Such compounds ought to be included in a forthcoming extended register. Enlarging the selection criteria to <C20 chains, to xenobiotic C,H,O carotenoids, considering heteroatoms outside the carotenoid carbon skeleton sphere and taking into account ionic bounded heteroatoms is desirable for future compilation [36,37]. It would furthermore be valuable to have at hand a complete directory of isotope-substituted carotenoids (D, T, 13C, 14C) [38,39,40]. A catalog of modified carotenoids (e.g., long chain carotenoids, carotenoid dimers, carotenoids with deviated conjugation, hydrophilic carotenoids) and of compounds where carotenoids are part of other molecule classes (e.g., carotenoid lipids, antioxidant combinations) would likewise be desirable [41,42,43,44,45,46,47,48,49,50,51].

4. Nomenclature

The designation “xenobiotic carotenoids” is synonymously used with the term “heterocarotenoids”.

Whereas “heterocarotenoids” may appear more precise, the prefix hetero- is too strongly linked with heterocyclic chemistry and could create confusing expressions such as heterocyclic heterocarotenoids. Xenobiotic is, at present, the more explanatory designation.

Applying the nomenclature rules to xenobiotic carotenoids can lead to unintelligible descriptions; consequently, many authors have avoided naming their products, e.g., 11Cl-15Cl [52]. Keeping in mind that a short trivial name engenders more associative information than a (semi)systematic designation, some names in the list may appear randomly chosen or meaningless. A name search in a database will, therefore, often be unsuccessful, e.g., the name dicyano-C48:15 for 9N is certainly not canonical, but articulates the essential information: a dicyano substituted carotenoid of 48 C with 15 conjugated double bonds. The exact name would hide this evidence. In any case, the interested reader should certainly scrutinize the carotenoids visually and not by their appellation, and a structure search in a database is, therefore, recommended. The structures are approximately listed according to increasing structural complexity; however, the relation to a parent compound was considered more important than complexity ranking.

Aryl carotenoids have been recorded separately within a heteroatom section. Natural occurring aryl carotenoids display trimethylbenzene ɸ− or χ− end groups. Phenyl end groups without methyl are identified as either 16,17,18-trinor-ɸ− or 16,17,18-trinor-χ−; nevertheless, the letter ɸ is preferred, in analogy to the widely used short form of ɸ for °phenyl [53]. Thus, all carotenoids with a benzene ring are termed ɸ-carotenoids; the ɸ-ring positions are indicated as recommended by the nomenclature rule.

The compounds were arbitrarily numbered; the numbers are not intended to reflect the appointed personal identification digits used in the Key to Carotenoids and the Carotenoids Handbook [4,5]. Carotenoids with heterocycles were, for example, enumerated as x◉S, ◉S indicating a cycle with sulfur.

The catalog of xenobiotic carotenoids definitely proves that the termxanthophyll has become obsolete [54]. Applying the classical two level differentiation − hydrocarbon carotenoids (C, H) and xanthophylls (C,H,O)—simply implies denying the existence of the listed 178 carotenoids. The use of xanthophyll is therefore discouraged and should be replaced by oxygen carotenoids; such a designation is unequivocally extendable to sulfur (nitrogen, halogen…) carotenoids.

5. Conclusions

Xenobiotic carotenoids have been synthesized for a long time but have remained largely unnoticed by carotenoid chemists. Many of those who work with these compounds may not consider themselves carotenoid chemists. Heteroatoms have helped carotenoids to leave their terrain of origin: xenobiotic carotenoids merit the same appreciation as biotic carotenoids.

6. List of Xenobiotic Carotenoids

6.1. Halogen-Carotenoids

6.1.1. Fluorine F

1F 9-trifluoromethyl-β,β-carotene C40H53F3

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

2F 13-trifluoromethyl-β,β-carotene C40H53F3

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

3F 9,9'-bis(trifluoromethyl)-β-carotene C40H50F6

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

4F 13,13'-bis(trifluoromethyl)-β-carotene C40H50F6

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

5F 9-trifluoromethyl echinenone C40H51F3O

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

6F 13-trifluoromethyl echinenone C40H51F3O

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

7F 9-trifluoromethyl canthaxanthin C40H49F3O2

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

8F 13-trifluoromethyl canthaxanthin C40H49F3O2

D. Hoischen, L.U. Colmenares, I. Koukhareva, M. Ho, R.S.H. Liu, J. Fluorine Chem. 1999, 97, 165

9F 3,3'-difluoro-canthaxanthin C40H50F2O2

R.S.H. Liu, J. Liu, J. Nat. Prod. 2011, 74, 512

10F 10-fluoro-astaxanthin C40H51FO4

R.S.H. Liu, J. Liu, J. Nat. Prod. 2011, 74, 512

11F 14-fluoro-astaxanthin C40H51FO4

R.S.H. Liu, J. Liu, J. Nat. Prod. 2011, 74, 512

12F 3,3',10,10',14-pentafluoro-canthaxanthin C40H47F5O2

R.S.H. Liu, J. Liu, J. Nat. Prod. 2011, 74,512

ɸ-carotenoids

13F 1',2',3',4',5'-pentafluoro-β,ɸ-carotene C37H41F5

E. Hand, K.A. Belmore, L.D. Kispert, Helv. Chim. Acta 1993, 76, 1928

6.1.2. Chlorine Cl

1Cl crocetin dichloride C20H22Cl2O2

H. Pfander, F. Wittwer, Helv. Chim. Acta 1979, 62, 1944

2Cl norbixin dichloride C24H26Cl2O2

L. Levy, R.H. Binnington, A. Tabatnik, WO 02/068385, 2002

3Cl bixin chloride C25H29ClO3

G. Ferrari, V. Vecchietti, EP 30009, 1981

T. Komatsu, E. Tsuchia, C. Böttcher, D. Donner, C. Messerschmidt, U. Siggel, W. Stocker, J.P. Rabe, J.H. Fuhrhop, J. Am. Chem. Soc. 1997, 119, 11660

4Cl β-apo-8'-carotenoyl chloride, C30-acid chloride C30H39ClO

T. Naalsund, K.E. Malterrud, V. Partali, H.R. Sliwka, Chem. Phys. Lipids 2001, 112, 59

L. Levy, R. H. Binnington, A. Tabatnik, WO 02/068385, 2002

5Cl 4-chloro-β,β-carotene C40H55Cl

H. Pfander, U. Leuenberger, Chimia 1976, 30, 71

6Cl 4-chloro-3',4'-didehydro-β,β-carotene C40H53Cl

H. Pfander, U. Leuenberger, Chimia 1976, 30, 71

7Cl 4'-chloro-β,β-caroten-3-ol C40H55ClO

H. Pfander, U. Leuenberger, Chimia 1976, 30, 71

8Cl 4,4'-dichloro-β,β-carotene C40H54Cl2

H. Pfander, U. Leuenberger, Chimia 1976, 30, 71

9Cl 5,5'-dichloro-4,5,4',5'-tetrahydroisocarotene C41H58Cl2

C. Bodea, E. Nicoara, Acad. rep. populare Romîne, Filiala Cluj, Studii Cercetâri Chim. 1959, 10, 1959

10Cl 7-chloro-mutatoxanthin-3,3'-diacetate C44H59ClO5

J.E. Johansen, S. Liaaen-Jensen, Acta Chem. Scand. 1974, B28, 949

R. Buchecker, S. Liaaen-Jensen, Helv. Chim. Acta 1975, 58, 89

11Cl 3'-chloro-4,5-dehydro-5-dehydroxy-neochrome C37H49ClO2

R. Buchecker, S. Liaaen-Jensen, Helv. Chim. Acta 1975, 58, 89

12Cl 3'-chloro-2,3-didehydro-5,18-dehydro-5-dehydroxy-neochrome C37H47ClO

R. Buchecker, S. Liaaen-Jensen, Helv. Chim. Acta 1975, 58, 89

13Cl 7-chloro-mutatoxanthin-19',11'-olide 3-acetate C42H53ClO6

J.E. Johansen, S. Liaaen-Jensen, Acta Chem. Scand. 1974, B28, 949

14Cl 3'-chloro-6,7-didehydro-peridinol-3-acetate C42H53ClO6

J.E. Johansen, S. Liaaen-Jensen, Acta Chem. Scand. 1974, B28, 949

15Cl 4,5-didehydro-5-dehydroxy-3'-chloro-peridinin-3-acetate C42H51ClO5

J.E. Johansen, S. Liaaen-Jensen, Acta Chem. Scand. 1974, B28, 949

6.1.3. Bromine Br

1Br 20-bromo-crocetindial C20H23BrO2

J.E. Johansen, S. Liaaen-Jensen, Acta Chem. Scand. 1975, B29, 315

2Br 20,20'-dibromo-crocetindial C20H22Br2O2

J.E. Johansen, S. Liaaen-Jensen, Acta Chem. Scand. 1975, B29, 315

3Br 4-bromo-β,β-carotene C40H55Br

R. Entschel, P. Karrer, Helv. Chim. Acta 1958, 41, 983

J. Morel, DE2001957, 1970

4 Br 4,4'-dibromo-β,β-carotene C40H58Br2

R. Entschel, P. Karrer, Helv. Chim. Acta 1958, 41, 402

C. Martin, P. Karrer, Helv. Chim. Acta 1959, 42, 464

5Br 4-bromo-4'-ethoxy-β,β-carotene C42H59BrO

R. Entschel, P. Karrer, Helv. Chim. Acta 1958, 41, 402

6Br 4-bromo-4'-ethoxy-β,β-carotene C44H63BrO2

R. Entschel, P. Karrer, Helv. Chim. Acta 1958, 41, 402

7Br 4-bromo-4-ethoxy echinenone C42H57BrO2

R. Entschel, P. Karrer, Helv. Chim. Acta 1958, 41, 402

8Br 4 bromo-4',4'-diethoxy-β,β-carotene C44H63BrO2

F.J. Petracek, L. Zechmeister, J. Am. Chem. Soc. 1956, 78, 1427

9Br 4,4,4'-tribromo-β,β-carotene C40H53Br3

F.J. Petracek, L. Zechmeister, J. Am. Chem. Soc. 1956, 78, 1427

10Br 7-bromo-mutatoxanthin-diacetate C44H59BrO5

R. Buchecker, S. Liaaen-Jensen, Helv. Chim. Acta 1975, 58, 89

6.1.4. Iodine I

1I 5,5'-diiodo-5,6,5',6'-didehydro-β,β-carotene C40H58I2

unconfirmed structure

B.G. Savinov, G.S. Tretyakova, Vitaminy Akad. Nauk Ukr. S.S.R 1953, 1, 137

Other carotenoid-iodine compounds are formulated as ionic complexes:

B.F. Lutnaes, J. Krane, S. Liaaen-Jensen, Org. Biomol. Chem. 2004, 2, 2821

6.2. Silicon-Carotenoids Si

1Si (= 2◉S) 7,5'-diapo-7-thienyl-carotene-5'-triethoxysilane C34H46O3SSi

F. Effenberger, M. Wezstein, Synthesis 2001, 1368

6.3. Nitrogen-Carotenoids N

1N 8'-apo-β-carotene-8'-nitrile C30H39N

Z. He, D. Gosztola, Y. Deng, G. Gao, M.R. Wasielewski, L.D. Kispert, J. Phys. Chem. B 2000, 104, 6668

2N 10'-apo-5,6-seco-β-carotene-10'-nitrile C27H35NO2

R. Kuhn, H. Brockmann, Chem. Ber. 1934, 67, 885

3N 6'-apo-β-carotene-6'-nitrile C32H41N

Z. He, D. Gosztola, Y. Deng, G. Gao, M.R. Wasielewski, L.D. Kispert, J. Phys. Chem. B 2000, 104, 6668

S. Tretiak, V. Chernyak, S. Mukamel, J. Am. Chem. Soc. 1997, 119, 11408

S. Gilmour, S.R. Marder, B.G. Tiemann, L.T. Cheng, J. Chem. Soc. Chem. Commun. 1993, 432

4N 4'-apo-β-carotene-4'-nitrile C34H43N

Z. He, D. Gosztola, Y. Deng, G. Gao, M.R. Wasielewski, L.D. Kispert, J. Phys. Chem.B2000, 104, 6668

5N 7'-cyano-β-apo-7'-carotenoic acid methyl ester C34H43NO2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

6N 7'-apo-7',7'-dicyano-β−carotene C33H40N2

M. Blanchard-Desce, I. Ledoux, J.M. Lehn, J. Malthête, J. Zyss, J. Chem. Soc. Chem. Commun. 1988, 737

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

M.P. O’Neil, M.R. Nasielewski, M.M. Khaled, L.D. Kispert, J. Chem.Phys. B, 1991, 95, 7212

S. Gilmour, S.R. Marder, B.G. Tiemann, L.T. Cheng, J. Chem. Soc. Chem. Commun. 1993, 432

E.S. Hand, K.A. Belmore, L.D. Kispert, J. Chem.Soc. Perkin Trans 2, 1993, 659

S. Tretiak, V. Chernyak, S. Mukamel, J. Am. Chem. Soc. 1997, 119, 11408

A.J. Cruz, K. Siam, D.P. Rillema, J. Phys. Chem. 2011, 115, 1108

7N 4,14'-dicyano-20,20’-dinor-β,β-carotene- C40H50N2

H.H. Haeck, T. Kralt, Rec. Trav. Chim. Pays-Bas 1966, 85, 343

P.B. Braun, J. Hornstra, J.I. Leenhouts, Acta Cryst. 1971, B27, 90

8N dicyano-C44:14 C48H60N2

H.H. Haeck, T. Kralt, Rec. Trav. Chim. Pays-Bas 1966, 85, 343

9N dicyano-C48:15 C52H66N2

H.H. Haeck, T. Kralt, Rec. Trav. Chim. Pays-Bas 1966, 85, 343

10N (3S)-2',3’-didehydro-β,β-carotene-3-amine C40H55N

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

11N (3R,3'S)-3'-amino-β,β-carotene-3-ol C40H57NO

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

12N (3S,3'S)-β,β-carotene-3,3'-amine C40H58N2

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

J. Inananga, M. Yamaguchi, Mem. Fac. Sci. Kyushi Univ. Ser. C, 1989, 17, 109

13N (3S,3'S)-β,β-carotene-3,3'-diacetamide C44H62N2O2

J. Inananga, M. Yamaguchi, Mem. Fac. Sci. Kyushi Univ. Ser. C, 1989, 17, 109

14N 4,4'-dianilino-β,β-carotene C52H66N2

C. Martin, P. Karrer, Helv. Chim. Acta 1959, 42, 464

H. Budzikiewicz, H.Brzezinka, B. Johannes, Monatshefte 1970, 101, 579

15N 4,4'-bis(N-methyl-anilino)-β,β-carotene C54H70N2

C. Martin, P. Karrer, Helv. Chim. Acta 1959, 42, 464

16N (3S)-3-azido-2',3'-didehydro-β,β-carotene C40H53N3

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

17N (3R,3'S)-3'-azido-β,β-carotene-3-ol C40H55N3O

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

18N (3S,3'S)-diazido-β,β-carotene C40H54N6

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

J. Inananga, M. Yamaguchi, Mem. Fac. Sci. Kyushi Univ. Ser. C, 1989, 17, 109

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

19N 8'-apo-β-caroten-8'-aldoxime hydrochloride, C30-aldoxime hydrochloride C30H42ClNO

J. Willibald, S. Rennebaum, S. Breukers, S.H. Abdel Hafez, A. Patel, C.L. Øpstad, R. Schmid, S. Nalum Naess, H.R. Sliwka, V. Partali, Chem. Phys. Lipids 2009, 161, 32

H.R. Sliwka, V. Partali, S.F. Lockwood, in Carotenoids, ed. J.T. Landrum, CRC Press, Boca Raton, USA, 2010, chpt. 3

20N echinenenon oxime hydrochloride C40H56ClNO

J. Willibald, S. Rennebaum, S. Breukers, S.H. Abdel Hafez, A. Patel, C.L. Øpstad, R. Schmid, S. Nalum Naess, H.R. Sliwka, V. Partali, Chem. Phys. Lipids 2009, 161, 32

H.R. Sliwka, V. Partali, S.F. Lockwood, in Carotenoids, ed. J.T. Landrum, CRC Press, Boca Raton, USA, 2010, chpt. 3

21N canthaxanthin dioxime hydrochloride C40H56Cl2N2O2

J. Willibald, S. Rennebaum, S. Breukers, S.H. Abdel Hafez, A. Patel, C.L. Øpstad, R. Schmid, S. Nalum Naess, H.R. Sliwka, V. Partali, Chem. Phys. Lipids 2009, 161, 32

H.R. Sliwka, V. Partali, S.F. Lockwood, in Carotenoids, ed. J.T. Landrum, CRC Press, Boca Raton, USA, 2010, chpt. 3

22N astaxanthin dioxime hydrochloride C40H56Cl2N2O4

J. Willibald, S. Rennebaum, S. Breukers, S.H. Abdel Hafez, A. Patel, C.L. Øpstad, R. Schmid, S. Nalum Naess, H.R. Sliwka, V. Partali, Chem. Phys. Lipids 2009, 161, 32

H.R. Sliwka, V. Partali, S.F. Lockwood, in Carotenoids, ed. J.T. Landrum, CRC Press, Boca Raton, USA, 2010, chpt. 3

23N 7'-aza-7'-methyl-7'-apo-β-carotene C31H43N

G.A.J. Pitt, F.D. Collins, R.A. Morton, P. Stok, Biochem. J. 1955, 59, 122

24N 7'-aza-7'-butyl-7'-apo-β-carotene C34H49N

T.A. Moore, P.S. Song, J. Mol. Spec. 1974, 52, 224

25N 7'-aza-7'-butyl-7'-apo-β-carotene hydrochloride C35H52ClN

T.A. Moore, P.S. Song, J. Mol. Spec. 1974, 52, 224

26N 5'-aza-5'-butyl-5'-apo-β-carotene C37H53N

T.A. Moore, P.S. Song, J. Mol. Spec. 1974, 52, 224

27N 5'-aza-5'-butyl-5'-apo-β-carotene hydrochloride C37H54ClN

T.A. Moore, P.S. Song, J. Mol. Spec. 1974, 52, 224

28N 5'-aza-5'-butyl-5'-apo-β-caroten-3-ol C36H51NO

T.A. Moore, P.S. Song, J. Mol. Spec. 1974, 52, 224

29N 5'-aza-5'-butyl-5'-apo-β-caroten-3-ol hydrochloride C36H52ClNO

T.A. Moore, P.S. Song, J. Mol. Spec. 1974, 52, 224

30N 7'-aza-7'-ureido-7'-apo-β-caroten-3-ol, β-citraurin semicarbazone C31H43N3O2

L. Zechmeister, L. von Cholnoky, Liebigs Ann. 1937, 530, 291

31N 7'-nitro-7'-apo-β-carotene C31H41NO2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

32N 4-nitro-β,β-carotene C40H55NO2

D.L. Baker, E.S. Kroll, N. Jacobsen, D.C. Liebler, Chem. Res. Toxicol. 1999, 12, 535

33N 11-nitroastaxanthin C40H51NO6

R. Yoshioka, T. Hayakawa, K. Ishuzuka, A. Kulkarni, Y. Terada, T. Maoka, H. Etoh, Tetrahedron Lett. 2006, 47, 3637 (cis-isomer)

34N 15-nitroastaxanthin C40H51NO6

R. Yoshioka, T. Hayakawa, K. Ishuzuka, A. Kulkarni, Y. Terada, T. Maoka, H. Etoh, Tetrahedron Lett. 2006, 47, 3637 (cis-isomer)

35N 12-nitrocapsanthin C40H55NO5

M. Tsuboi, H. Etoh, K. Kato, H. Nakatugawa, H. Kato, Y. Maejima, G. Matsumoto, H. Mori, M. Hosokawa, K. Miyashita, H. Tokuda, N. Suzui, T. Maoka, J. Agric. Food Chem. 2011, 59, 10572

36N 11-nitrofucoxanthin C42H57NO8

M. Tsuboi, H. Etoh, K. Kato, H. Nakatugawa, H. Kato, Y. Maejima, G. Matsumoto, H. Mori, M. Hosokawa, K. Miyashita, H. Tokuda, N. Suzui, T. Maoka, J. Agric. Food Chem. 2011, 59, 10572

37N 15-nitrofucoxanthin C42H57NO8

M. Tsuboi, H. Etoh, K. Kato, H. Nakatugawa, H. Kato, Y. Maejima, G. Matsumoto, H. Mori, M. Hosokawa, K. Miyashita, H. Tokuda, N. Suzui, T. Maoka, J. Agric. Food Chem. 2011, 59, 10572

38N 16,16'-diaza-β,β-carotene (diretinyliden hydrazine) C40H56N2

T. Miki, Y. Hara, JP 34-002118, 1959

T. Miki, Y. Hara, Chem. Pharm. Bull. 1962, 10, 922

39N 5-acetyl-2-nor-β-apo-7'-carotenoic acid amide C32H41NO2

R. Kuhn, H. Brockmann, Chem. Ber. 1934, 67, 885

40N N-hexyl crocetinamide C26H35NO3

G. Quinkert, K.R. Schmieder, G. Dürner, K. Hache, A. Stegk, D.H.R. Barton, Chem. Ber. 1977, 110, 3582

41N β-apo-7'-benzoylamino-7'-carotenoic acid N,N-diethylamide C43H56N2O2

M. Tomoaia-Cotisel, J. Zsako, E. Chifu, D.A. Ladenhead, Langmuir 1990,6,191. The authors list several related amides.

42N β-apo-7'-benzoylamido-7'-carotenoic acid N-aminoethylamide C41H53N3O2

M. Tomoaia-Cotisel, J. Zsako, E. Chifu, D.A. Ladenhead, Langmuir 1990,6,191

43N β-apo-7'-benzoylamido-7'-carotenoic acid N-methyl-N-(2-hydroxyethyl)-amide C42H54N2O3

M. Tomoaia-Cotisel, J. Zsako, E. Chifu, D.A. Ladenhead, Langmuir 1990,6,191

44N β-apo-7'-benzoylamido-7'-carotenoic acid N,N-(bis(2-hydroxyethyl)-amide C43H56N2O4

M. Tomoaia-Cotisel, J. Zsako, E. Chifu, D.A. Ladenhead, Langmuir 1990,6,191

45N N-octadecyl bixinamide C42H65NO3

J.H. Fuhrhop, M. Krull, A. Schulz, D. Möbius, Langmuir 1990, 6,497. The authors list several related bixin amides.

G. Ferrari, V. Vecchietti, EP 030009, 1980 describe numerous bixin amides.

46N dibixine diphenylenediamid C54H60N2O6

J.H. Fuhrhop, M. Krull, A. Schulz, D. Möbius, Langmuir 1990, 6, 497

47N imine of tris-(8,8'-diapo-ψ,ψ-carotene-8.8'-diimine) C72H96N8

J.M. Lehn, J.P. Vigneron, I. Bkouhe-Waksman, J. Guilhem, C. Pascal, Helv. Chim. Acta 1992, 75, 1069

ɸ-carotenoids

48N 7'-aza-3'-methyl-β,ɸ-carotene C37H47N

H. Kamogawa, Polym. Lett. Ed. 1972, 10, 929

49N 7'-aza-3'-dimethylamino-β,ɸ-carotene C36H46N2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

50N 7'-aza-β,ɸ-caroten-3'-amine C36H46N2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

51N 7'-aza-3'-methoxy-β,ɸ-carotene C37H47NO

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

52N β,ɸ-carotene-3'-acetamide C39H49NO

M.R. Wasielewski, P.A. Liddel, D. Barrett, T.A. Moore, D. Gust, Nature 1986, 322, 570

53N β,ɸ-carotene-3'-porphyrinamide

D. Gust, T.A. Moore, P.A. Liddell, G.A. Nemeth, L.R. Makings, A.L. Moore, D. Barrett, P.J. Pessiki, R.V. Bemasson, M. Rougiée, C. Chachaty, F.C. De Schryver, M. Van der Auweraer, A.R. Holzwarth, J. S. Connolly, J. Am. Chem. Soc. 1987, 109, 846

54N 3'-nitro-β,ɸ-carotene C37H45NO2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

S. Gilmour, S.R. Marder, B.G. Tiemann, L.T. Cheng, J. Chem. Soc. Chem. Commun. 1993, 432

E.S. Hand, K.A. Belmore, L.D. Kispert, Helv. Chim. Acta 1993, 76, 1928

55N 1',3'-dinitro-β,ɸ-carotene C37H44N2O4

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

56N 2-dimethylamino-ɸ,ɸ-carotene-3'-nitrile C37H40N2

A. Slama-Schwok, M. Blanchard-Desce, J.M Lehn, J. Phys. Chem. 1990, 94, 3894

57N 3'-nitro-ɸ,ɸ-carotene-2-dimethylamine C36H40N2O2

A. Slama-Schwok, M. Blanchard-Desce, J.M Lehn, J. Phys. Chem. 1990, 94, 3894

58N 7'-cyano-3'-nitro-β,ɸ-carotene C38H44N2O2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

59N 7'-cyano-7'-benzoxo-β-carotene C39H45NO

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

60N 3'-dimethylamino-β,ɸ-carotene C39H51N

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

61N 3'-dioctylamino-β,ɸ-carotene C53H79N

T. Wagner, S. Roth, Synth. Metals 1993, 54, 307

62N 2',3'-dicyano-β,ɸ-carotene C39H44N2

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

6.3. Chalcogen-Carotenoids

6.3.1. Sulfur S

1S echinenone thione C40H54S

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1994, 48, 679

2S canthaxanthin thione C40H52OS

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1994, 48, 679

3S rhodoxanthin thione C40H50OS

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1994, 48, 679

4S 3'-thiolutein C40H56OS

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1990, 44, 61

5S (3S)-2',3'-didehydro-β,β-carotene-3-thiol C40H54S

H.R. Sliwka, S. Liaaen-Jensen, Tetrahdron Asym. 1993, 4, 361

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

6S (3R,3'S)-3'-sulfanyl-β,β-caroten-3-ol C40H56OS

H.R. Sliwka, S. Liaaen-Jensen, Tetrahdron Asym. 1993, 4, 361

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

7S 3'-thioacetyl lutein C42H58O2S

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1990, 44, 61

8S 4,4'-dithioacetyl-β,β-carotene C44H60O2S2

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

9S 4'-thioacethyl-β,β-caroten-4-one C42H56O2S

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1990, 44, 61

10S (3R)-3',4'-didehydro-3-phenylsulfanyl-β,β-carotene C46H58S

J. Inananga, M. Yamaguchi, Mem. Fac. Sci. Kyushi Univ. Ser. C, 1989, 17, 109

11S 3,3'-diphenylsulfanyl-β,β-carotene C52H64S2

J. Inananga, M. Yamaguchi, Mem. Fac. Sci. Kyushi Univ. Ser. C, 1989, 17, 109

12S 4,4'-diphenylsulfanyl-β,β-carotene C52H64S2

C. Martin, P. Karrer, Helv. Chim. Acta 1959, 42, 464

13S 3,4'-dehydro-β,β-carotene-4-thioglucopyranoside C74H80O9S

V. Nagy, A. Agócs, E. Turcsi, J. Deli, Tetrahedron Lett. 2010, 52, 1020

14S β,β,-carotene-4,4'-bisthioglucopyranoside C107H106O18S2

V. Nagy, A. Agócs, E. Turcsi, J. Deli, Tetrahedron Lett. 2010, 52, 1020

15S β,β-carotene-15-yl-phenylsulfone C46H60O2S

K. Berhard, S. Jäggli, P. Kreienbühl, U. Schwieter, EU298404, 1989. The patent lists numerous other phenylsulfones and p-chlorophenylsulfones as synthetic intermediates.

ɸ-carotenoids

16S 3-methylsulfanyl-8'-apo-ɸ-carotenal C28H32OS

Y.Q. Shen, W. Göhring, S. Hagen, S. Roth, J. Mol. Electron. 1990, 6, 31

17S β,ɸ-carotene-3'-methanethiol C38H48S

G. Leatherman, E.N. Duranti, D. Gust, T.A. Moore, A.L. Moore, S. Stone, Z. Zhou, P. Rez, Y.Z. Liu, S.M. Lindsay, J. Phys. Chem. B 1999, 103, 4006

18S 10,10'-dimethyl-13-phenyl-9,9',13,13'-tetranor-ɸ,ɸ−carotene-3,3'-dimethanethiol C40H40S2

J. Maeng, S.B. Kim, N.J. Lee, E. Choi, S.Y. Jung, I. Hong, S.H. Bae, J.T. Oh, B. Lim, J.W. Kim, C.J. Kang, S. Koo, Chem. Eur. J. 2010, 16, 7395. The authors list other similar compounds.

6.3.1. Selenium Se

1Se (3S)-2',3'-didehydro-β,β-carotene-3-phenylselenide C46H58Se

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1995, 49, 428

E. Oliveros, A.M. Braun, T. Aminian-Saghafi, H.R. Sliwka, New J. Chem. 1994, 18, 535

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

2Se zeaxanthin phenylselenide, (3R,3'S)-3'-phenylseleno-β,β-caroten-3-ol C46H60OSe

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1995, 49, 428

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

3Se zeaxanthin diphenylselenide, (3S,3'S)-β,β-carotene-3,3'-diphenylselenide C52H64Se2

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1995, 49, 428

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

4Se lutein phenylselenide, (3R,3'R,S,6'R)-3'-phenyleleno-β,ε-caroten-3-ol C46H60OSe

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1995, 49, 428

5Se rhodoxanthin diphenylselenide, 7,7'-di(phenylseleno)-7,8,7',8'-dihydro-retro-ε,ε-carotene-

3,3'-dione C52H62O2Se2

postulated unstable intermediate

H.R. Sliwka, S. Liaaen-Jensen, Acta Chem. Scand. 1995, 49, 856

6Se (3S)-2',3'-didehydro-β,β-caroten-3-yl-di-O,O-propylselenophosphate C46H67O3PSe

H.R. Sliwka, Acta Chem. Scand. 1997, 51, 345

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

7Se (3R,3'S)-3-hydroxy-3-yl-di-O,O-propylselenophosphate C46H69O4PSe

H.R. Sliwka, Acta Chem. Scand. 1997, 51, 345

H.R. Sliwka, Helv. Chim. Acta 1999, 82, 161

6.4. Combinations

6.4.1. Nitrogen, Sulfur N,S

1NS zeaxanthin thiocyanate, (3S)-3'-thiocyano-β,β-caroten-3-ol C41H55NOS

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

2NS zeaxanthin dithiocyanat, (3S,3'S)-β,β-carotene-3,3'-dithiocyanate C42H54N2S2

H.R. Sliwka, S. Liaaen-Jensen, Tetrahedron Asym. 1993, 4, 2377

6.5. Iron Fe

1Fe ferrocenyl-C21 aldehyde, 7-ferrocenyl-7,8'-diapocaroten-8'-al C31H35FeO

F. Effenberger, H. Schlosser, Synthesis 1990, 1085

2Fe ferrocenyl-C31 aldehyde C41H47FeO

F. Effenberger, H. Schlosser, Synthesis 1990, 1085

3Fe C22 bis(ferrocenyl), 7,7'-bis(ferrocenyl)-7,7'-diapocarotene C42H48Fe

F. Effenberger, H. Schlosser, Synthesis 1990, 1085

4Fe C26 bis(ferrocenyl) C46H52Fe2

J.M. Lehn, Angew. Chem. Int. Ed. 1990, 29, 1304

5Fe tetrakis(iron tricarbonyl)-β,β-carotene C52H56Fe4O12

M. Ichikawa, M. Tsutsui, F. Vohwinkel, Z. Naturforschg. 1967, 22b, 376

6Fe tetrakis(iron tricarbonyl)-β,β-carotene C52H56Fe4O12

M. Ichikawa, M. Tsutsui, F. Vohwinkel, Z. Naturforschg. 1967, 22b, 376

7Fe tetrakis(iron tricarbonyl)-β,β-carotene C52H56Fe4O12

M. Ichikawa, M. Tsutsui, F. Vohwinkel, Z. Naturforschg. 1967, 22b, 376

6.6. Heterocycle Carotenoids

6.6.1. N-heterocycle ◉N

1◉N crocetin-di-imidazolide C26H30N4O2

H. Pfander, F. Wittwer, Helv. Chim. Acta 1979, 62, 1944

2◉N crocetin-bis(1,2,4-triazolide) C26H30N4O2

H. Pfander, F. Wittwer, Helv. Chim. Acta 1979, 62, 1944

3◉N octadexylbixin imidazolide C45H67N3O2

J.H. Fuhrhop, M. Krull, A. Schulz, D. Möbius, Langmuir 1990, 6,497

4◉N N-(8'-apo-β-carotene-8-ylidene)-pyrrolidium perchlorate C34H48ClNO4

D.L. Coffen, E. Ho, C. Nocka, G. Sasso, V. Toome, T.R. Wagler, T.H. Williams, J. Prakt. Chem. 1993, 335, 135

5◉N 7'-apo-7'-(N-methyl-4-pyridinium)-β-carotene iodide C37H48IN

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

6◉N 7'-apo-7'-(N-methyl-2-pyridinium)-β-carotene iodide C37H48IN

H. Ikeda, T. Sakai, Y. Kawabe, JP 2-2534, 1990

7◉N 7,7'-diapo-7,7'-bis(2-pyridyl)-carotene C32H34N2

H.R. Brahmana, K. Katsuyama, J. Inaga, T. Katsuki, M. Yamaguchi, Tetrahedron Lett. 1981, 22, 1695

8◉N 7,7'-diapo-7,7'-bis(3-pyridyl)-carotene C32H34N2

H.R. Brahmana, K. Katsuyama, J. Inaga, T. Katsuki, M. Yamaguchi, Tetrahedron Lett. 1981, 22, 1695

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

9◉N 7,7'-diapo-7,7'-bis(4-pyridyl)-carotene C32H34N2

I. Visoly-Fisher, K. Daie, Y. Terazono, C. Herrero, F. Fungo, L. Otero, E. Durantini, J.J. Silber, L. Sereno, D. Gust, T.A. Moore, A.L. Morre, S.M. Lindsay, PNAS 2006, 103, 8686

10◉N bis(4-pyridyl)-C26:11-carotene C36H38N2

I. Visoly-Fisher, K. Daie, Y. Terazono, C. Herrero, F. Fungo, L. Otero, E. Durantini, J.J. Silber, L. Sereno, D. Gust, T.A. Moore, A.L. Morre, S.M. Lindsay, PNAS 2006, 103, 8686

11◉N bis(4-pyridyl)-C26:11-carotene C36H38N2

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

12◉N bis(4-pyridyl)-C34:15-carotene C36H38N2

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

13◉N 1,4-bis(4-pyridyl-C12:5)-benzene C40H40N2

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

14◉N 1,4-bis(4-pyridinium-C12:5)-benzene diiodide C42H46I2N2

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

15◉N 7,7'-diapo-7,7'-bis(4-methylpyridinium)-carotene diiodide C34H40I2N2

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

16◉N 7,7'-diapo-7,7'-bis(4-ethylpyridinium)-carotene dibromide C36H44Br2N2

T. Okumoto, N. Morita, I. Nakamura, M. Konishi, M. Yamaguchi, J. Cancer Res.. Clin. Oncol. 1985, 109, 257

17◉N bis(4-pyridinium)-C34:15-carotene diiodide C38H44I2N2

T.S. Arrhenius, M. Blanchard-Desce, M. Dvolaitzky, J.M. Lehn, J. Malthête, Proc. Natl. Acad. Sci. USA 1986, 83, 5355

18◉N 7,7'-diapo-7,7'-bis(1,3,3 trimethylindolenium)-carotene dichlorate C42H48Cl2N2O8

S. Hünig, F. Linhart, D. Scheutzow, Liebigs Ann. 1975, 2089

19◉N 7,7'-diapo-7'-(4-pyridyl)-ɸ-carotene-2-dimethylamine C35H40N2

M. Blanchard-Desce, J.M. Lehn, I. Ledoux, J. Zyss, Special Publication - Royal Society of Chemistry (Org. Mater. Non-linear Opt.) 1989, 69, 170

20◉N 7'-cyano-7'-(4-pyridyl)-β,ɸ-carotene C37H44N2

A.J. Cruz, K. Siam, D.P. Rillema, J. Phys. Chem. 2011, 115, 1108

21◉N lutein-6H-1,2-oxazine C39H53NO3

M. Tsuboi, H. Etoh, Y. Yomoda, K. Kato, H. Kato, A. Kulkarni, Y. terada, T. Maoka, H. Mori, T. Inakuma, Tetrahedron Lett. 2010, 521, 676

22◉N 6,6'-diapocarotenal-6'-(2-phenyl-azlactone) C33H33NO3

J. Zsako, M. Tomoaia-Cotisel, V. Tamas, C. Coman, E. Chifu, Rev. Roum. Chim. 1987, 32, 1193.

The authors describe several other azlactones.

23◉N β-apo-6'-carotenal-2-phenyl-azlactone C39H45NO2

V. Tamas, V. Ciurdaru, C. Bodea, Rev. Roum. Chim. 1973, 18, 1409

24◉N β-apo-6'-carotendial bis-2-phenyl diazlactone, C24:11 diazlactone C42H38N2O4

V. Tamas, V. Ciurdaru, C. Bodea, Rev. Roum. Chim. 1973, 18, 1409

25◉N C30:13-diazlactone C48H48N2O4

V. Tamas, V. Ciurdaru, C. Bodea, Rev. Roum. Chim. 1973, 18, 1409. The authors describe several other azlactones.

26◉N bis(2,2'-bipyridine-4-yl)-carotene C42H40N4

F. Effenberger, M. Wezstein, Synthesis 2001, 1368

27◉N astacene bisphenazine C52H56N4

P. Karrer, L. Loewe, Helv. Chim. Acta 1934, 17, 745

S. Hertzberg, S. Liaaen-Jensen, C.R. Enzell, G.W. Francis, Acta Chem. Scand. 1969, 23, 3290

28◉N violerythrin bisquinoxaline C50H52N4

S. Hertzberg, S. Liaaen-Jensen, C.R. Enzell, G.W. Francis, Acta Chem. Scand. 1969, 23, 3290

29◉N 7,7'-diapo-7',7'-dicyano-7-julolidinyl-carotene C36H39N3

M. Blanchard-Desce, J.M. Lehn, M. Barzoukas, I. Ledoux, J. Zyss, Chem. Phys. 1994, 181, 281

30◉N 7'-apo-3-cyano-7'-julolidinyl-ɸ−carotene C41H44N2

M. Blanchard-Desce, J.M. Lehn, M. Barzoukas, I. Ledoux, J. Zyss, Chem. Phys. 1994, 181, 281

31◉N 7'-apo-7'-julolidinyl-3-nitro-ɸ-carotene C40H44N2O2

M. Blanchard-Desce, J.M. Lehn, M. Barzoukas, I. Ledoux, J. Zyss, Chem. Phys. 1994, 181, 281

32◉N diterpyridine carotenoid C52H46N6

G. Pickaert, R. Ziessel, Tetrahedron Lett. 1998, 39, 3497

6.6.2. S-heterocycle ◉S

1◉S 3,4,3',4',-tetrahydrospirilloxanthin-20-(1,3-dithiolane) C44H66O2S2

A.J. Aasen, S. Liaaen Jensen, Acta Chem. Scand. 1967, 21, 2185

2◉S (= 1Si) 7,5'-diapo-7-thienyl-carotene-5'-triethoxysilane C34H46O3SSi

F. Effenberger, M. Wezstein, Synthesis 2001, 1368

3◉S 7,7'-diapo-bis(2-thienyl)-carotene C30H32S2

H.R. Brahmana, K. Katsuyama, J. Inaga, T. Katsuki, M. Yamaguchi, Tetrahedron Lett. 1981, 22, 1695

F. Effenberger, M. Wezstein, Synthesis 2001, 1368

4◉S 7,7'-diapo-bis(3-thienyl)-carotene C30H32S2

H.R. Brahmana, K. Katsuyama, J. Inaga, T. Katsuki, M. Yamaguchi, Tetrahedron Lett. 1981, 22, 1695

5◉S 7',8-diapo-7',7'-dicyano-8-(benzodithiol-2-ylidene)-carotene C30H28N2S2

M. Blanchard-Desce, I. Ledoux, J. Malthête, J. Zyss, J. Chem. Soc., Chem. Commun. 1988, 737

6◉S 8'-apo-8'-(benzodithiol-2-ylidene)-3-cyano-ɸ−carotene C35H33NS2

M. Blanchard-Desce, I. Ledoux, J. Malthête, J. Zyss, J. Chem. Soc., Chem. Commun. 1988, 737

7◉S 8'-apo-8'-(benzodithiol-2-ylidene)-3-nitro-ɸ-carotene C34H33NO2S2

M. Blanchard-Desce, I. Ledoux, J. Malthête, J. Zyss, J. Chem. Soc., Chem. Commun. 1988, 737

6.6.3. N,S-heterocycle ◉N,S

1◉N,S 7,8'-diapo-8'-(benzodithiol-2-ylidene)-7-(4-pyridyl)-carotene C33H33NS2

M. Blanchard-Desce, I. Ledoux, J. Malthête, J. Zyss, J. Chem. Soc., Chem. Commun. 1988, 737

2◉N,S 7,8'-diapo-8'-(benzodithiol-2-ylidene)-7-(4-pyridinium)-carotene iodide C34H36INS2

M. Blanchard-Desce, I. Ledoux, J. Malthête, J. Zyss, J. Chem. Soc., Chem. Commun. 1988, 737

3◉N,S C30-aldehyde rhodanine, 8'-apo-β-carotenyliden-rhodanine C33H41NOS2

H. Hegedus, US3071583, 1963

H. Thommen, Int. Z. Vitaminforsch. 1967, 37, 175