The tripeptide N-Cbz-βGly-Gly-Gly-Obz.

The title peptide, N-benzyl-oxycarbonyl-β-glycylglycylglycine benzyl ester, C22H25N3O6, contains a non-proteinogenic amino acid residue, β-glycine, which is a homologated analogue of glycine. In the mol-ecular structure, β-glycine adopts an extended conformation with a trans conformation about its C(β)-C(α) bond. The second glycine residue adopts an extended conformation while the third glycine residue adopts a helical conformation. In the crystal, three N-H⋯O hydrogen bonds, two involving the same carbonyl O atom as acceptor, results in an infinite two-dimensional network parallel to the bc plane.

Related literature

For comprehensive reviews on β-amino acids and β-peptides, see: Cheng et al. (2001 ▸); Seebach et al. (2004 ▸). For conformations and structural features of β-peptides, see: Appella et al. (1996 ▸, 1997 ▸); Seebach & Matthews (1997 ▸); Gellman (1998 ▸); Hill et al. (2001 ▸); Seebach et al. (1996 ▸, 2005 ▸, 2006 ▸). For the conformations of hybrid peptide sequences formed of α-, β- and higher ω-amino acids, see: Banerjee & Balaram (1997 ▸); Karle et al. (1997 ▸); Gopi et al. (2002 ▸); Roy & Balaram (2004 ▸); Ananda et al. (2005 ▸); Roy et al. (2005 ▸); Schmitt et al. (2005 ▸, 2006 ▸); Sharma et al. (2009 ▸); Schramm et al. (2010 ▸).

Experimental

Crystal data

C22H25N3O6

M = 427.45

Monoclinic,

a = 24.713 (3) Å

b = 9.6794 (10) Å

c = 8.9445 (10) Å

β = 92.257 (5)°

V = 2137.9 (4) Å3

Z = 4

Mo Kα radiation

μ = 0.10 mm−1

T = 293 K

0.4 × 0.2 × 0.04 mm

Data collection

Bruker Kappa APEXII CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2001 ▸) T min = 0.623, T max = 0.746

17172 measured reflections

5253 independent reflections

2790 reflections with I > 2σ(I)

R int = 0.031

Refinement

R[F 2 > 2σ(F 2)] = 0.096

wR(F 2) = 0.326

S = 1.06

5253 reflections

300 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.36 e Å−3

Δρmin = −0.48 e Å−3

Data collection: APEX2 (Bruker, 2007 ▸); cell refinement: SAINT-Plus (Bruker, 2007 ▸); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▸) and Mercury (Macrae et al., 2006 ▸); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989015004272/lr2132sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015004272/lr2132Isup2.hkl

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989015004272/lr2132Isup3.docx

Click here for additional data file.

Supporting information file. DOI: 10.1107/S2056989015004272/lr2132Isup4.docx

Click here for additional data file.

. DOI: 10.1107/S2056989015004272/lr2132fig1.tif

Thermal Ellipsoid plot of NCbz-β Gly-Gly-Gly-Obz drawn at 50% probability level. Hydrogen atoms have been omitted for clarity.

Click here for additional data file.

. DOI: 10.1107/S2056989015004272/lr2132fig2.tif

A view of the packing of NCbz-βGly-Gly-Gly-Obz as viewed down the b-axis. Inter­molecular hydrogen bonds are represented as dotted lines.

Click here for additional data file.

. DOI: 10.1107/S2056989015004272/lr2132fig3.tif

Atomic labeling and definition of backbone torsion angles in case of β-residues.

CCDC reference: 1051721

Additional supporting information: crystallographic information; 3D view; checkCIF report

C22H25N3O6	Z = 4
Mr = 427.45	F(000) = 904
Monoclinic, P21/c	Dx = 1.328 Mg m−3
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 24.713 (3) Å	µ = 0.10 mm−1
b = 9.6794 (10) Å	T = 293 K
c = 8.9445 (10) Å	Platy, colourless
β = 92.257 (5)°	0.4 × 0.2 × 0.04 mm
V = 2137.9 (4) Å3

Bruker Kappa APEXII CCD diffractometer	5253 independent reflections
Radiation source: fine-focus sealed tube	2790 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
φ and ω scan	θmax = 29.0°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −32→32
Tmin = 0.623, Tmax = 0.746	k = −12→12
17172 measured reflections	l = −11→11

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.096	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.326	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ2(Fo2) + (0.1714P)2 + 1.0437P] where P = (Fo2 + 2Fc2)/3
5253 reflections	(Δ/σ)max = 0.002
300 parameters	Δρmax = 0.36 e Å−3
0 restraints	Δρmin = −0.48 e Å−3

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.

	x	y	z	Uiso*/Ueq
H1	−0.1225 (17)	0.939 (5)	0.538 (4)	0.076 (13)*
H3	0.1457 (19)	0.725 (5)	0.070 (5)	0.090 (14)*
H2	0.0217 (15)	1.030 (4)	0.199 (4)	0.065 (10)*
H5	0.0956 (12)	0.980 (3)	0.076 (3)	0.049 (8)*
H4	0.0636 (16)	0.839 (4)	0.028 (5)	0.080 (11)*
O1	0.00828 (10)	0.7312 (2)	0.2548 (3)	0.0649 (7)
O2	0.12260 (10)	0.8556 (2)	0.3578 (2)	0.0591 (6)
N2	0.03006 (12)	0.9470 (3)	0.1942 (3)	0.0547 (7)
O08	−0.19841 (12)	0.8357 (2)	0.6131 (3)	0.0756 (8)
C2'	0.11788 (14)	0.8269 (3)	0.2236 (3)	0.0493 (7)
N3	0.14819 (13)	0.7339 (3)	0.1580 (3)	0.0570 (7)
C2A	0.07814 (14)	0.9016 (3)	0.1194 (3)	0.0513 (8)
C1'	−0.00243 (15)	0.8557 (3)	0.2570 (3)	0.0556 (8)
N1	−0.12109 (16)	0.8660 (3)	0.5058 (4)	0.0796 (11)
O0	−0.15371 (13)	0.6498 (3)	0.5322 (3)	0.0879 (9)
O4	0.27562 (12)	0.5598 (3)	0.2021 (3)	0.0794 (8)
C3A	0.19058 (15)	0.6565 (3)	0.2351 (3)	0.0618 (9)
H3A1	0.1777	0.5640	0.2558	0.074*
H3A2	0.2000	0.7008	0.3298	0.074*
C3'	0.24000 (15)	0.6480 (3)	0.1422 (3)	0.0576 (8)
C1A	−0.05199 (16)	0.9118 (3)	0.3264 (4)	0.0690 (10)
H1A1	−0.0438	1.0014	0.3701	0.083*
H1A2	−0.0803	0.9244	0.2493	0.083*
O3	0.24681 (12)	0.7125 (3)	0.0322 (3)	0.0932 (10)
C02	−0.27765 (19)	0.9393 (4)	0.8130 (4)	0.0769 (11)
H02	−0.2429	0.9693	0.8405	0.092*
C41	0.37438 (18)	0.5699 (4)	0.2075 (4)	0.0718 (11)
C01	−0.28408 (18)	0.8251 (4)	0.7229 (4)	0.0675 (10)
C07	−0.23646 (18)	0.7421 (4)	0.6764 (5)	0.0773 (11)
H07A	−0.2198	0.6951	0.7623	0.093*
H07B	−0.2479	0.6733	0.6030	0.093*
C0'	−0.15636 (17)	0.7739 (3)	0.5494 (4)	0.0674 (10)
C05	−0.3807 (2)	0.8538 (5)	0.7305 (5)	0.0931 (13)
H05	−0.4155	0.8253	0.7019	0.112*
C1B	−0.0713 (2)	0.8209 (5)	0.4406 (5)	0.0958 (16)
H1B1	−0.0435	0.8126	0.5196	0.115*
H1B2	−0.0771	0.7298	0.3976	0.115*
C42	0.3766 (2)	0.6760 (5)	0.3076 (5)	0.0898 (14)
H42	0.3455	0.7262	0.3262	0.108*
C47	0.32398 (19)	0.5314 (5)	0.1195 (5)	0.0872 (13)
H47A	0.3223	0.5830	0.0264	0.105*
H47B	0.3251	0.4338	0.0950	0.105*
C04	−0.3732 (2)	0.9655 (5)	0.8217 (6)	0.0973 (15)
H04	−0.4031	1.0124	0.8565	0.117*
C03	−0.3215 (2)	1.0095 (5)	0.8629 (5)	0.0915 (13)
H03	−0.3165	1.0865	0.9241	0.110*
C46	0.4205 (2)	0.4963 (5)	0.1821 (6)	0.0921 (13)
H46	0.4192	0.4236	0.1140	0.110*
C06	−0.3362 (2)	0.7829 (4)	0.6806 (5)	0.0812 (12)
H06	−0.3412	0.7067	0.6184	0.097*
C44	0.4706 (3)	0.6345 (6)	0.3560 (6)	0.1102 (17)
H44	0.5030	0.6563	0.4069	0.132*
C45	0.4691 (2)	0.5289 (6)	0.2569 (7)	0.1087 (16)
H45	0.5003	0.4787	0.2391	0.130*
C43	0.4254 (3)	0.7092 (6)	0.3820 (6)	0.1114 (19)
H43	0.4270	0.7824	0.4493	0.134*

	U11	U22	U33	U12	U13	U23
O1	0.0805 (17)	0.0314 (10)	0.0850 (16)	0.0001 (10)	0.0296 (13)	0.0009 (10)
O2	0.0866 (17)	0.0504 (11)	0.0408 (10)	0.0104 (11)	0.0110 (10)	−0.0026 (8)
N2	0.0747 (19)	0.0301 (11)	0.0610 (14)	0.0063 (12)	0.0226 (13)	0.0056 (10)
O08	0.0919 (19)	0.0478 (12)	0.0901 (17)	0.0053 (12)	0.0418 (15)	−0.0023 (11)
C2'	0.073 (2)	0.0336 (12)	0.0429 (13)	−0.0043 (13)	0.0195 (13)	0.0007 (10)
N3	0.080 (2)	0.0487 (14)	0.0428 (13)	0.0124 (13)	0.0082 (12)	−0.0041 (11)
C2A	0.069 (2)	0.0389 (13)	0.0473 (14)	0.0048 (14)	0.0177 (14)	0.0096 (12)
C1'	0.073 (2)	0.0342 (13)	0.0610 (16)	0.0038 (14)	0.0187 (15)	0.0019 (12)
N1	0.102 (3)	0.0498 (16)	0.091 (2)	0.0121 (17)	0.053 (2)	0.0010 (16)
O0	0.109 (2)	0.0499 (14)	0.107 (2)	0.0084 (14)	0.0342 (18)	−0.0139 (13)
O4	0.0870 (18)	0.0826 (17)	0.0705 (14)	0.0332 (15)	0.0259 (13)	0.0257 (13)
C3A	0.084 (2)	0.0523 (17)	0.0496 (15)	0.0149 (17)	0.0118 (15)	0.0027 (13)
C3'	0.076 (2)	0.0447 (15)	0.0525 (16)	−0.0003 (15)	0.0087 (15)	0.0006 (13)
C1A	0.074 (2)	0.0430 (16)	0.092 (2)	0.0066 (16)	0.0323 (19)	0.0056 (16)
O3	0.088 (2)	0.110 (2)	0.0832 (18)	0.0185 (17)	0.0207 (15)	0.0444 (17)
C02	0.092 (3)	0.060 (2)	0.080 (2)	0.000 (2)	0.022 (2)	−0.0021 (18)
C41	0.095 (3)	0.0567 (19)	0.0655 (19)	0.0159 (19)	0.027 (2)	0.0156 (16)
C01	0.087 (3)	0.0499 (17)	0.0670 (19)	−0.0021 (18)	0.0212 (18)	0.0065 (15)
C07	0.087 (3)	0.0515 (18)	0.095 (3)	0.0002 (19)	0.027 (2)	0.0023 (18)
C0'	0.091 (3)	0.0515 (18)	0.0609 (18)	0.0132 (18)	0.0239 (18)	−0.0045 (14)
C05	0.097 (3)	0.083 (3)	0.101 (3)	0.002 (3)	0.015 (3)	0.013 (3)
C1B	0.110 (4)	0.081 (3)	0.100 (3)	0.039 (3)	0.062 (3)	0.032 (2)
C42	0.113 (4)	0.071 (2)	0.088 (3)	0.011 (3)	0.034 (3)	0.003 (2)
C47	0.097 (3)	0.095 (3)	0.072 (2)	0.034 (3)	0.026 (2)	0.008 (2)
C04	0.108 (4)	0.073 (3)	0.114 (3)	0.013 (3)	0.040 (3)	0.011 (3)
C03	0.115 (4)	0.065 (2)	0.097 (3)	0.000 (3)	0.038 (3)	−0.009 (2)
C46	0.102 (4)	0.069 (2)	0.107 (3)	0.015 (3)	0.017 (3)	−0.008 (2)
C06	0.099 (3)	0.064 (2)	0.082 (2)	−0.009 (2)	0.016 (2)	−0.0005 (19)
C44	0.111 (4)	0.105 (4)	0.116 (4)	−0.017 (3)	0.023 (3)	−0.006 (3)
C45	0.094 (4)	0.092 (3)	0.140 (4)	0.012 (3)	0.011 (3)	−0.014 (3)
C43	0.140 (5)	0.090 (3)	0.108 (4)	−0.016 (3)	0.043 (4)	−0.023 (3)

O1—C1'	1.234 (3)	C02—H02	0.9300
O2—C2'	1.234 (3)	C41—C42	1.362 (6)
N2—C1'	1.333 (4)	C41—C46	1.371 (6)
N2—C2A	1.454 (4)	C41—C47	1.495 (6)
N2—H2	0.83 (4)	C01—C06	1.389 (6)
O08—C0'	1.345 (4)	C01—C07	1.497 (5)
O08—C07	1.438 (4)	C07—H07A	0.9700
C2'—N3	1.323 (4)	C07—H07B	0.9700
C2'—C2A	1.511 (5)	C05—C04	1.362 (7)
N3—C3A	1.441 (4)	C05—C06	1.386 (6)
N3—H3	0.79 (5)	C05—H05	0.9300
C2A—H5	0.96 (3)	C1B—H1B1	0.9700
C2A—H4	1.07 (4)	C1B—H1B2	0.9700
C1'—C1A	1.496 (5)	C42—C43	1.391 (8)
N1—C0'	1.317 (5)	C42—H42	0.9300
N1—C1B	1.449 (5)	C47—H47A	0.9700
N1—H1	0.76 (4)	C47—H47B	0.9700
O0—C0'	1.214 (4)	C04—C03	1.384 (8)
O4—C3'	1.324 (4)	C04—H04	0.9300
O4—C47	1.456 (5)	C03—H03	0.9300
C3A—C3'	1.506 (5)	C46—C45	1.388 (8)
C3A—H3A1	0.9700	C46—H46	0.9300
C3A—H3A2	0.9700	C06—H06	0.9300
C3'—O3	1.183 (4)	C44—C45	1.352 (7)
C1A—C1B	1.444 (5)	C44—C43	1.359 (8)
C1A—H1A1	0.9700	C44—H44	0.9300
C1A—H1A2	0.9700	C45—H45	0.9300
C02—C03	1.369 (6)	C43—H43	0.9300
C02—C01	1.373 (5)
C1'—N2—C2A	120.7 (2)	O08—C07—H07A	110.2
C1'—N2—H2	118 (3)	C01—C07—H07A	110.2
C2A—N2—H2	121 (3)	O08—C07—H07B	110.2
C0'—O08—C07	114.5 (3)	C01—C07—H07B	110.2
O2—C2'—N3	123.5 (3)	H07A—C07—H07B	108.5
O2—C2'—C2A	121.8 (3)	O0—C0'—N1	126.4 (3)
N3—C2'—C2A	114.7 (2)	O0—C0'—O08	122.7 (4)
C2'—N3—C3A	123.7 (3)	N1—C0'—O08	110.9 (3)
C2'—N3—H3	120 (3)	C04—C05—C06	119.7 (5)
C3A—N3—H3	116 (3)	C04—C05—H05	120.1
N2—C2A—C2'	112.6 (2)	C06—C05—H05	120.1
N2—C2A—H5	109.7 (18)	C1A—C1B—N1	114.3 (3)
C2'—C2A—H5	109.6 (18)	C1A—C1B—H1B1	108.7
N2—C2A—H4	105 (2)	N1—C1B—H1B1	108.7
C2'—C2A—H4	113 (2)	C1A—C1B—H1B2	108.7
H5—C2A—H4	106 (3)	N1—C1B—H1B2	108.7
O1—C1'—N2	120.5 (3)	H1B1—C1B—H1B2	107.6
O1—C1'—C1A	122.7 (3)	C41—C42—C43	120.1 (5)
N2—C1'—C1A	116.8 (3)	C41—C42—H42	120.0
C0'—N1—C1B	119.8 (3)	C43—C42—H42	120.0
C0'—N1—H1	118 (3)	O4—C47—C41	111.7 (3)
C1B—N1—H1	119 (3)	O4—C47—H47A	109.3
C3'—O4—C47	117.6 (3)	C41—C47—H47A	109.3
N3—C3A—C3'	110.8 (3)	O4—C47—H47B	109.3
N3—C3A—H3A1	109.5	C41—C47—H47B	109.3
C3'—C3A—H3A1	109.5	H47A—C47—H47B	107.9
N3—C3A—H3A2	109.5	C03—C04—C05	120.4 (5)
C3'—C3A—H3A2	109.5	C03—C04—H04	119.8
H3A1—C3A—H3A2	108.1	C05—C04—H04	119.8
O3—C3'—O4	124.2 (3)	C04—C03—C02	119.7 (4)
O3—C3'—C3A	125.1 (3)	C04—C03—H03	120.2
O4—C3'—C3A	110.7 (3)	C02—C03—H03	120.2
C1B—C1A—C1'	111.8 (3)	C41—C46—C45	120.7 (5)
C1B—C1A—H1A1	109.3	C41—C46—H46	119.7
C1'—C1A—H1A1	109.3	C45—C46—H46	119.7
C1B—C1A—H1A2	109.3	C01—C06—C05	120.4 (4)
C1'—C1A—H1A2	109.3	C01—C06—H06	119.8
H1A1—C1A—H1A2	107.9	C05—C06—H06	119.8
C03—C02—C01	121.1 (5)	C45—C44—C43	120.8 (6)
C03—C02—H02	119.5	C45—C44—H44	119.6
C01—C02—H02	119.5	C43—C44—H44	119.6
C42—C41—C46	119.2 (5)	C44—C45—C46	119.3 (6)
C42—C41—C47	123.1 (4)	C44—C45—H45	120.3
C46—C41—C47	117.6 (4)	C46—C45—H45	120.3
C02—C01—C06	118.7 (4)	C44—C43—C42	119.9 (5)
C02—C01—C07	121.4 (4)	C44—C43—H43	120.1
C06—C01—C07	119.8 (3)	C42—C43—H43	120.1
O08—C07—C01	107.7 (3)
O2—C2'—N3—C3A	−0.8 (5)	C07—O08—C0'—O0	7.7 (6)
C2A—C2'—N3—C3A	176.5 (3)	C07—O08—C0'—N1	−174.6 (4)
C1'—N2—C2A—C2'	−61.0 (4)	C1'—C1A—C1B—N1	−176.6 (4)
O2—C2'—C2A—N2	−31.3 (4)	C0'—N1—C1B—C1A	146.5 (5)
N3—C2'—C2A—N2	151.4 (3)	C46—C41—C42—C43	0.4 (6)
C2A—N2—C1'—O1	1.2 (5)	C47—C41—C42—C43	−177.8 (4)
C2A—N2—C1'—C1A	−177.8 (3)	C3'—O4—C47—C41	119.7 (4)
C2'—N3—C3A—C3'	−137.2 (3)	C42—C41—C47—O4	−31.4 (5)
C47—O4—C3'—O3	−5.8 (6)	C46—C41—C47—O4	150.4 (4)
C47—O4—C3'—C3A	175.3 (3)	C06—C05—C04—C03	0.9 (7)
N3—C3A—C3'—O3	10.8 (5)	C05—C04—C03—C02	−0.8 (7)
N3—C3A—C3'—O4	−170.4 (3)	C01—C02—C03—C04	−0.2 (7)
O1—C1'—C1A—C1B	25.1 (6)	C42—C41—C46—C45	−0.1 (7)
N2—C1'—C1A—C1B	−155.9 (4)	C47—C41—C46—C45	178.2 (4)
C03—C02—C01—C06	1.1 (6)	C02—C01—C06—C05	−1.0 (6)
C03—C02—C01—C07	−175.8 (4)	C07—C01—C06—C05	176.0 (4)
C0'—O08—C07—C01	−172.3 (3)	C04—C05—C06—C01	0.0 (6)
C02—C01—C07—O08	−52.3 (5)	C43—C44—C45—C46	−0.5 (9)
C06—C01—C07—O08	130.8 (4)	C41—C46—C45—C44	0.1 (8)
C1B—N1—C0'—O0	−5.3 (7)	C45—C44—C43—C42	0.9 (9)
C1B—N1—C0'—O08	177.1 (4)	C41—C42—C43—C44	−0.8 (7)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O1i	0.83 (4)	2.13 (4)	2.951 (3)	169 (4)
N3—H3···O2ii	0.79 (5)	2.11 (5)	2.868 (3)	161 (5)
N1—H1···O2iii	0.76 (5)	2.20 (5)	2.959 (4)	176 (2)

Table 1

Hydrogen-bond geometry (, )

DHA	DH	HA	D A	DHA
N2H2O1i	0.83(4)	2.13(4)	2.951(3)	169(4)
N3H3O2ii	0.79(5)	2.11(5)	2.868(3)	161(5)
N1H1O2iii	0.76(5)	2.20(5)	2.959(4)	176(2)

Symmetry codes: (i) ; (ii) ; (iii) .