Literature DB >> 21589625

A functionalized enol lactone containing a protected α-amino acid.

Giuseppe Bruno, Francesco Nicoló, Massimiliano Cordaro, Giovanni Grassi, Francesco Risitano.   

Abstract

The crystal structure of N-(3,9-dimethyl-4-phenyl-2,5-dioxo-3,4-dihydro-2H,5H-pyrano[3,2-c]chromen-3-yl)-N-methylbenzamide methanol monosolvate, C(28)H(23)NO(5)·CH(3)OH, has been determined at room temperature by X-ray diffraction. Structural parameters are discussed with reference to ab initio calculations.

Entities:  

Year:  2010        PMID: 21589625      PMCID: PMC3011768          DOI: 10.1107/S1600536810043709

Source DB:  PubMed          Journal:  Acta Crystallogr Sect E Struct Rep Online        ISSN: 1600-5368


Related literature

For structures containing enol lactone fragments, see: Murray et al. (1982 ▶); Harborne & Baxter (1999 ▶); Qabaja et al. (2000 ▶). For related structures containing a coumarin fragment, see: Yu et al. (2003 ▶). For a phenyl­furo[3,2-c]chromen-4-one structure, see: Bruno et al. (2001 ▶). For related furan-5-one structures, see: Grassi et al. (2002 ▶). For the Cambridge Structural Database, see: Allen (2002 ▶). For the GAUSSIAN98 software used for the ab initio calculations, see: Frisch et al. (1998 ▶). For the synthetic process used, see: Grassi et al. (2003 ▶). For background to O—C—O bond-angle asymmetry, see: Kokila et al. (1996 ▶).

Experimental

Crystal data

C28H23NO5·CH4O M = 485.52 Monoclinic, a = 10.7435 (14) Å b = 9.9056 (17) Å c = 23.298 (3) Å β = 94.817 (7)° V = 2470.7 (6) Å3 Z = 4 Mo Kα radiation μ = 0.09 mm−1 T = 298 K 0.58 × 0.38 × 0.36 mm

Data collection

Siemens P4 diffractometer Absorption correction: ψ scan (Kopfmann & Huber, 1968 ▶) T min = 0.870, T max = 0.968 9535 measured reflections 4347 independent reflections 2843 reflections with I > 2σ(I) R int = 0.036 3 standard reflections every 197 reflections intensity decay: none

Refinement

R[F 2 > 2σ(F 2)] = 0.049 wR(F 2) = 0.132 S = 1.01 4347 reflections 331 parameters H-atom parameters constrained Δρmax = 0.18 e Å−3 Δρmin = −0.31 e Å−3 Data collection: XSCANS (Bruker, 1999 ▶); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 2008 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: XPW (Siemens, 1996 ▶); software used to prepare material for publication: PARST97 (Nardelli, 1995 ▶) and SHELXL97. Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810043709/jh2217sup1.cif Structure factors: contains datablocks I. DOI: 10.1107/S1600536810043709/jh2217Isup2.hkl Additional supplementary materials: crystallographic information; 3D view; checkCIF report
C28H23NO5·CH4OF(000) = 1024
Mr = 485.52Dx = 1.305 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 59 reflections
a = 10.7435 (14) Åθ = 7.7–17.5°
b = 9.9056 (17) ŵ = 0.09 mm1
c = 23.298 (3) ÅT = 298 K
β = 94.817 (7)°Irregular, colourless
V = 2470.7 (6) Å30.58 × 0.38 × 0.36 mm
Z = 4
Siemens P4 diffractometer2843 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.036
graphiteθmax = 25.0°, θmin = 2.0°
ω scansh = −12→12
Absorption correction: ψ scan (Kopfmann & Huber, 1968)k = −1→11
Tmin = 0.870, Tmax = 0.968l = −27→27
9535 measured reflections3 standard reflections every 197 reflections
4347 independent reflections intensity decay: none
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.049H-atom parameters constrained
wR(F2) = 0.132w = 1/[σ2(Fo2) + (0.0533P)2 + 0.7913P] where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max = 0.001
4347 reflectionsΔρmax = 0.18 e Å3
331 parametersΔρmin = −0.31 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0036 (8)
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.
xyzUiso*/UeqOcc. (<1)
O10.50718 (15)0.77955 (19)0.49310 (6)0.0560 (5)
C20.6021 (2)0.8610 (3)0.51636 (10)0.0490 (6)
C30.64762 (19)0.8378 (2)0.57594 (9)0.0440 (6)
C40.5962 (2)0.7392 (2)0.60580 (9)0.0456 (6)
C50.4958 (2)0.6556 (3)0.58143 (10)0.0483 (6)
C60.4409 (2)0.5503 (3)0.61028 (12)0.0588 (7)
H60.46840.53270.64850.071*
C70.3471 (2)0.4720 (3)0.58354 (14)0.0675 (8)
C80.3087 (2)0.5014 (3)0.52619 (15)0.0735 (9)
H80.24510.45000.50750.088*
C90.3612 (2)0.6034 (3)0.49630 (12)0.0655 (8)
H90.33400.62030.45800.079*
C100.4550 (2)0.6802 (3)0.52418 (10)0.0512 (6)
O110.64195 (16)0.9454 (2)0.48534 (7)0.0649 (5)
C120.75139 (19)0.9241 (3)0.60261 (9)0.0442 (6)
H120.73801.01540.58720.053*
C130.7374 (2)0.9318 (3)0.66888 (9)0.0447 (6)
C140.7351 (2)0.7859 (3)0.68848 (9)0.0491 (6)
O150.64021 (15)0.70590 (17)0.66098 (6)0.0538 (4)
C160.2891 (3)0.3579 (3)0.61477 (16)0.0964 (11)
H16A0.24610.29840.58730.145*0.50
H16B0.23100.39380.63990.145*0.50
H16C0.35330.30870.63700.145*0.50
H16D0.30750.36890.65550.145*0.50
H16E0.32260.27350.60290.145*0.50
H16F0.20030.35850.60580.145*0.50
C170.8802 (2)0.8790 (3)0.58752 (9)0.0493 (6)
C180.9676 (2)0.9762 (3)0.57662 (11)0.0684 (8)
H180.94681.06700.57890.082*
C191.0865 (3)0.9398 (4)0.56224 (12)0.0835 (10)
H191.14431.00640.55520.100*
C201.1177 (3)0.8095 (5)0.55848 (13)0.0848 (11)
H201.19710.78570.54900.102*
C211.0328 (3)0.7111 (4)0.56862 (13)0.0832 (10)
H211.05460.62070.56580.100*
C220.9136 (2)0.7461 (3)0.58313 (11)0.0633 (7)
H220.85630.67870.58990.076*
C230.8437 (2)1.0061 (3)0.70278 (10)0.0583 (7)
H23A0.84751.09730.68910.087*
H23B0.92120.96130.69770.087*
H23C0.82941.00670.74290.087*
N240.61573 (15)0.9977 (2)0.67699 (7)0.0444 (5)
C250.5853 (2)1.1225 (3)0.64515 (11)0.0613 (7)
H25A0.66051.17280.64120.092*
H25B0.52901.17560.66570.092*
H25C0.54671.10070.60760.092*
C260.5548 (2)0.9634 (3)0.72315 (10)0.0490 (6)
O270.59794 (16)0.8770 (2)0.75754 (7)0.0659 (5)
C280.4305 (2)1.0259 (3)0.73030 (10)0.0502 (6)
C290.3308 (2)1.0086 (3)0.68954 (12)0.0716 (8)
H290.34140.96150.65580.086*
C300.2151 (2)1.0614 (4)0.69901 (14)0.0843 (10)
H300.14771.04720.67190.101*
C310.1984 (3)1.1333 (4)0.74701 (14)0.0807 (9)
H310.12061.17000.75260.097*
C320.2965 (3)1.1516 (4)0.78720 (13)0.0806 (9)
H320.28561.20130.82030.097*
C330.4116 (2)1.0973 (3)0.77930 (11)0.0657 (8)
H330.47731.10910.80750.079*
O340.81109 (15)0.7302 (2)0.72014 (7)0.0637 (5)
C340.5741 (5)0.8527 (5)0.8947 (2)0.1397 (17)
H34A0.53250.78660.86980.210*
H34B0.52140.93050.89690.210*
H34C0.59150.81500.93250.210*
O350.6784 (3)0.8881 (7)0.87417 (13)0.208 (2)
H350.66750.89470.83900.312*
U11U22U33U12U13U23
O10.0512 (9)0.0702 (12)0.0453 (9)0.0038 (9)−0.0040 (7)−0.0002 (9)
C20.0414 (12)0.0628 (17)0.0433 (12)0.0088 (12)0.0060 (10)−0.0008 (13)
C30.0388 (11)0.0561 (15)0.0378 (11)0.0061 (11)0.0068 (9)0.0007 (11)
C40.0450 (12)0.0535 (15)0.0383 (11)0.0068 (12)0.0044 (9)−0.0019 (11)
C50.0400 (12)0.0528 (15)0.0533 (14)0.0048 (11)0.0110 (10)−0.0051 (12)
C60.0509 (14)0.0589 (17)0.0680 (16)0.0005 (13)0.0135 (12)−0.0055 (14)
C70.0489 (15)0.0576 (18)0.099 (2)−0.0006 (14)0.0214 (15)−0.0127 (17)
C80.0433 (14)0.074 (2)0.102 (2)−0.0026 (15)0.0015 (15)−0.0291 (19)
C90.0494 (15)0.076 (2)0.0696 (17)0.0070 (15)−0.0045 (13)−0.0197 (16)
C100.0397 (12)0.0585 (17)0.0553 (14)0.0072 (12)0.0041 (11)−0.0069 (13)
O110.0640 (11)0.0864 (14)0.0446 (9)−0.0029 (10)0.0072 (8)0.0148 (10)
C120.0405 (12)0.0535 (15)0.0390 (11)0.0011 (11)0.0058 (9)0.0027 (11)
C130.0387 (12)0.0575 (16)0.0382 (11)0.0040 (11)0.0043 (9)−0.0002 (11)
C140.0447 (12)0.0655 (17)0.0373 (11)0.0055 (13)0.0060 (10)0.0006 (12)
O150.0619 (10)0.0573 (11)0.0417 (8)−0.0035 (9)0.0011 (7)0.0069 (8)
C160.076 (2)0.076 (2)0.141 (3)−0.0171 (18)0.029 (2)−0.003 (2)
C170.0421 (12)0.0686 (18)0.0378 (12)−0.0006 (13)0.0079 (10)−0.0013 (12)
C180.0584 (16)0.086 (2)0.0632 (16)−0.0079 (16)0.0182 (13)−0.0048 (16)
C190.0550 (17)0.129 (3)0.0698 (19)−0.015 (2)0.0224 (14)−0.009 (2)
C200.0500 (16)0.138 (3)0.0687 (19)0.014 (2)0.0170 (14)−0.014 (2)
C210.0671 (19)0.103 (3)0.081 (2)0.027 (2)0.0170 (16)−0.0044 (19)
C220.0546 (15)0.073 (2)0.0631 (16)0.0080 (15)0.0110 (12)−0.0009 (14)
C230.0463 (13)0.0765 (19)0.0518 (13)−0.0025 (14)0.0015 (11)−0.0070 (14)
N240.0397 (10)0.0542 (12)0.0397 (9)0.0036 (9)0.0068 (8)0.0038 (9)
C250.0583 (15)0.0686 (19)0.0586 (15)0.0116 (14)0.0158 (12)0.0123 (14)
C260.0455 (13)0.0591 (16)0.0427 (12)0.0009 (12)0.0049 (10)−0.0023 (12)
O270.0669 (11)0.0826 (14)0.0501 (10)0.0178 (11)0.0156 (8)0.0156 (10)
C280.0417 (12)0.0607 (16)0.0490 (13)−0.0030 (12)0.0091 (10)0.0024 (12)
C290.0502 (15)0.100 (2)0.0642 (16)−0.0008 (16)0.0047 (12)−0.0214 (17)
C300.0403 (15)0.128 (3)0.084 (2)−0.0023 (17)−0.0005 (14)−0.011 (2)
C310.0505 (16)0.113 (3)0.081 (2)0.0139 (17)0.0204 (15)−0.002 (2)
C320.0637 (18)0.107 (3)0.0732 (19)0.0124 (18)0.0176 (15)−0.0207 (18)
C330.0503 (14)0.091 (2)0.0564 (15)0.0016 (15)0.0070 (12)−0.0154 (15)
O340.0554 (10)0.0799 (13)0.0549 (10)0.0163 (10)−0.0014 (8)0.0164 (10)
C340.159 (4)0.135 (4)0.128 (4)0.009 (4)0.024 (3)0.029 (3)
O350.140 (3)0.398 (7)0.0822 (19)0.048 (4)−0.0186 (19)0.013 (3)
O1—C101.369 (3)C18—H180.9300
O1—C21.376 (3)C19—C201.339 (5)
C2—O111.206 (3)C19—H190.9300
C2—C31.451 (3)C20—C211.369 (5)
C3—C41.344 (3)C20—H200.9300
C3—C121.498 (3)C21—C221.395 (4)
C4—O151.372 (3)C21—H210.9300
C4—C51.438 (3)C22—H220.9300
C5—C101.390 (3)C23—H23A0.9600
C5—C61.398 (3)C23—H23B0.9600
C6—C71.379 (4)C23—H23C0.9600
C6—H60.9300N24—C261.349 (3)
C7—C81.396 (4)N24—C251.464 (3)
C7—C161.507 (4)C25—H25A0.9600
C8—C91.375 (4)C25—H25B0.9600
C8—H80.9300C25—H25C0.9600
C9—C101.381 (4)C26—O271.236 (3)
C9—H90.9300C26—C281.493 (3)
C12—C171.524 (3)C28—C331.373 (3)
C12—C131.566 (3)C28—C291.382 (3)
C12—H120.9800C29—C301.383 (4)
C13—N241.488 (3)C29—H290.9300
C13—C141.516 (4)C30—C311.351 (4)
C13—C231.523 (3)C30—H300.9300
C14—O341.189 (3)C31—C321.362 (4)
C14—O151.403 (3)C31—H310.9300
C16—H16A0.9600C32—C331.374 (4)
C16—H16B0.9600C32—H320.9300
C16—H16C0.9600C33—H330.9300
C16—H16D0.9600C34—O351.302 (5)
C16—H16E0.9600C34—H34A0.9600
C16—H16F0.9600C34—H34B0.9600
C17—C221.371 (4)C34—H34C0.9600
C17—C181.382 (4)O35—H350.8200
C18—C191.395 (4)
C10—O1—C2122.43 (19)H16D—C16—H16F109.5
O11—C2—O1117.3 (2)H16E—C16—H16F109.5
O11—C2—C3125.1 (2)C22—C17—C18118.0 (2)
O1—C2—C3117.6 (2)C22—C17—C12123.1 (2)
C4—C3—C2119.4 (2)C18—C17—C12118.8 (2)
C4—C3—C12121.6 (2)C17—C18—C19120.9 (3)
C2—C3—C12119.0 (2)C17—C18—H18119.5
C3—C4—O15122.4 (2)C19—C18—H18119.5
C3—C4—C5122.8 (2)C20—C19—C18120.3 (3)
O15—C4—C5114.8 (2)C20—C19—H19119.9
C10—C5—C6118.7 (2)C18—C19—H19119.9
C10—C5—C4116.3 (2)C19—C20—C21120.1 (3)
C6—C5—C4124.9 (2)C19—C20—H20120.0
C7—C6—C5121.6 (3)C21—C20—H20120.0
C7—C6—H6119.2C20—C21—C22120.3 (3)
C5—C6—H6119.2C20—C21—H21119.9
C6—C7—C8117.5 (3)C22—C21—H21119.9
C6—C7—C16121.4 (3)C17—C22—C21120.5 (3)
C8—C7—C16121.2 (3)C17—C22—H22119.8
C9—C8—C7122.5 (3)C21—C22—H22119.8
C9—C8—H8118.8C13—C23—H23A109.5
C7—C8—H8118.8C13—C23—H23B109.5
C8—C9—C10118.8 (3)H23A—C23—H23B109.5
C8—C9—H9120.6C13—C23—H23C109.5
C10—C9—H9120.6H23A—C23—H23C109.5
O1—C10—C9117.6 (2)H23B—C23—H23C109.5
O1—C10—C5121.5 (2)C26—N24—C25121.0 (2)
C9—C10—C5120.9 (3)C26—N24—C13118.76 (19)
C3—C12—C17113.34 (19)C25—N24—C13117.86 (18)
C3—C12—C13107.90 (17)N24—C25—H25A109.5
C17—C12—C13113.96 (17)N24—C25—H25B109.5
C3—C12—H12107.1H25A—C25—H25B109.5
C17—C12—H12107.1N24—C25—H25C109.5
C13—C12—H12107.1H25A—C25—H25C109.5
N24—C13—C14110.10 (18)H25B—C25—H25C109.5
N24—C13—C23110.53 (19)O27—C26—N24120.7 (2)
C14—C13—C23109.6 (2)O27—C26—C28120.3 (2)
N24—C13—C12107.74 (16)N24—C26—C28118.9 (2)
C14—C13—C12104.82 (19)C33—C28—C29118.3 (2)
C23—C13—C12113.90 (18)C33—C28—C26120.2 (2)
O34—C14—O15117.1 (2)C29—C28—C26121.4 (2)
O34—C14—C13127.0 (2)C28—C29—C30119.9 (3)
O15—C14—C13115.49 (19)C28—C29—H29120.0
C4—O15—C14118.16 (18)C30—C29—H29120.0
C7—C16—H16A109.5C31—C30—C29121.0 (3)
C7—C16—H16B109.5C31—C30—H30119.5
H16A—C16—H16B109.5C29—C30—H30119.5
C7—C16—H16C109.5C30—C31—C32119.4 (3)
H16A—C16—H16C109.5C30—C31—H31120.3
H16B—C16—H16C109.5C32—C31—H31120.3
C7—C16—H16D109.5C31—C32—C33120.6 (3)
H16A—C16—H16D141.1C31—C32—H32119.7
H16B—C16—H16D56.3C33—C32—H32119.7
H16C—C16—H16D56.3C28—C33—C32120.7 (3)
C7—C16—H16E109.5C28—C33—H33119.6
H16A—C16—H16E56.3C32—C33—H33119.6
H16B—C16—H16E141.1O35—C34—H34A109.5
H16C—C16—H16E56.3O35—C34—H34B109.5
H16D—C16—H16E109.5H34A—C34—H34B109.5
C7—C16—H16F109.5O35—C34—H34C109.5
H16A—C16—H16F56.3H34A—C34—H34C109.5
H16B—C16—H16F56.3H34B—C34—H34C109.5
H16C—C16—H16F141.1C34—O35—H35109.5
C10—O1—C2—O11179.8 (2)N24—C13—C14—O1557.6 (2)
C10—O1—C2—C30.6 (3)C23—C13—C14—O15179.33 (17)
O11—C2—C3—C4−179.2 (2)C12—C13—C14—O15−58.1 (2)
O1—C2—C3—C4−0.1 (3)C3—C4—O15—C145.6 (3)
O11—C2—C3—C120.5 (3)C5—C4—O15—C14−177.71 (18)
O1—C2—C3—C12179.67 (19)O34—C14—O15—C4−144.9 (2)
C2—C3—C4—O15175.6 (2)C13—C14—O15—C428.2 (3)
C12—C3—C4—O15−4.2 (3)C3—C12—C17—C22−38.0 (3)
C2—C3—C4—C5−0.8 (3)C13—C12—C17—C2285.9 (3)
C12—C3—C4—C5179.5 (2)C3—C12—C17—C18140.8 (2)
C3—C4—C5—C101.1 (3)C13—C12—C17—C18−95.3 (3)
O15—C4—C5—C10−175.52 (19)C22—C17—C18—C19−0.7 (4)
C3—C4—C5—C6178.7 (2)C12—C17—C18—C19−179.5 (2)
O15—C4—C5—C62.0 (3)C17—C18—C19—C200.3 (5)
C10—C5—C6—C7−0.7 (4)C18—C19—C20—C210.1 (5)
C4—C5—C6—C7−178.2 (2)C19—C20—C21—C22−0.2 (5)
C5—C6—C7—C80.1 (4)C18—C17—C22—C210.6 (4)
C5—C6—C7—C16179.5 (2)C12—C17—C22—C21179.4 (2)
C6—C7—C8—C90.4 (4)C20—C21—C22—C17−0.1 (4)
C16—C7—C8—C9−178.9 (3)C14—C13—N24—C2635.9 (3)
C7—C8—C9—C10−0.4 (4)C23—C13—N24—C26−85.3 (3)
C2—O1—C10—C9−179.3 (2)C12—C13—N24—C26149.6 (2)
C2—O1—C10—C5−0.3 (3)C14—C13—N24—C25−161.6 (2)
C8—C9—C10—O1178.8 (2)C23—C13—N24—C2577.2 (2)
C8—C9—C10—C5−0.1 (4)C12—C13—N24—C25−47.8 (3)
C6—C5—C10—O1−178.3 (2)C25—N24—C26—O27−163.2 (2)
C4—C5—C10—O1−0.6 (3)C13—N24—C26—O27−1.3 (3)
C6—C5—C10—C90.7 (3)C25—N24—C26—C2820.1 (3)
C4—C5—C10—C9178.4 (2)C13—N24—C26—C28−177.9 (2)
C4—C3—C12—C1798.8 (2)O27—C26—C28—C3361.0 (4)
C2—C3—C12—C17−80.9 (3)N24—C26—C28—C33−122.4 (3)
C4—C3—C12—C13−28.3 (3)O27—C26—C28—C29−116.1 (3)
C2—C3—C12—C13151.9 (2)N24—C26—C28—C2960.5 (3)
C3—C12—C13—N24−62.3 (2)C33—C28—C29—C30−0.8 (4)
C17—C12—C13—N24170.9 (2)C26—C28—C29—C30176.3 (3)
C3—C12—C13—C1455.0 (2)C28—C29—C30—C311.9 (5)
C17—C12—C13—C14−71.8 (2)C29—C30—C31—C32−1.4 (5)
C3—C12—C13—C23174.7 (2)C30—C31—C32—C33−0.2 (5)
C17—C12—C13—C2347.9 (3)C29—C28—C33—C32−0.8 (4)
N24—C13—C14—O34−130.1 (2)C26—C28—C33—C32−177.9 (3)
C23—C13—C14—O34−8.3 (3)C31—C32—C33—C281.3 (5)
C12—C13—C14—O34114.3 (2)
D—H···AD—HH···AD···AD—H···A
O35—H35···O270.821.992.784 (3)163
C9—H9···O35i0.932.463.320 (4)153
C19—H19···O11ii0.932.603.403 (3)144
Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯AD—HH⋯ADAD—H⋯A
O35—H35⋯O270.821.992.784 (3)163
C9—H9⋯O35i0.932.463.320 (4)153
C19—H19⋯O11ii0.932.603.403 (3)144

Symmetry codes: (i) ; (ii) .

  5 in total

1.  The Cambridge Structural Database: a quarter of a million crystal structures and rising.

Authors:  Frank H Allen
Journal:  Acta Crystallogr B       Date:  2002-05-29

2.  A short history of SHELX.

Authors:  George M Sheldrick
Journal:  Acta Crystallogr A       Date:  2007-12-21       Impact factor: 2.290

3.  3-Phenyl-4H-furo[3,2-C]chromen-4-one.

Authors:  G Bruno; F Nicoló; A Rotondo; F Foti; F Risitano; G Grassi; C Bilardo
Journal:  Acta Crystallogr C       Date:  2001-04       Impact factor: 1.172

4.  Regio and diastereoselective lactonisation of enolisable 1,3-dicarbonyls by reaction with mesoionic 1,3-oxazolium-5-olates.

Authors:  Giovanni Grassi; Francesco Risitano; Francesco Foti; Massimiliano Cordaro; Giuseppe Bruno; Francesco Nicolò
Journal:  Chem Commun (Camb)       Date:  2003-08-07       Impact factor: 6.222

5.  Selectivity in the photodimerization of 6-alkylcoumarins.

Authors:  Xiuling Yu; Dieter Scheller; Otto Rademacher; Thomas Wolff
Journal:  J Org Chem       Date:  2003-09-19       Impact factor: 4.354

  5 in total

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