The desoxazoline asidiacyclamide analogue cyclo(Gly-Thr-D-Val-Thz-Ile-Thr-D-Val-Thz) acetonitrile monosolvate.

Akiko Asano,Mitsunobu Doi

doi:10.1107/s1600536811051543

Abstract

The title peptide [systematic name: 4-(butan-2-yl)-7,20-bis(1-hydroxyethyl)-10,23-bis(propan-2-yl)-12,25-dithia-3,6,9,16,19,22,27,28-octaazatricyclo[22.2.1.111,14]octacosa-1(26),11(28),13,24(27)-tetraene-2,5,8,15,18,21-hexone acetonitrile monosolvate], C32H48N8O8S2·CH3CN, an analogue of ascidiacyclamide (ASC) [cyclo(–Ile–Oxz–D-Val–Thz–)2], lies about a twofold rotation axis, so that the glycine (Gly) and isoleucine (Ile) residues are each disordered over two sites with equal occupancies. The acetonitrile molecule is also located on a twofold axis passing through the C and N atoms. In the peptide, the thiazole rings are faced to each other with a dihedral angle of 9.63 (15)° and intramolecular N—H⋯O and O—H⋯O hydrogen bonds are observed. A bifurcated N—H⋯(O,O) hydrogen bond links the peptide molecules into a layer parallel to the ab plane.

Highlights

N—H (O,O) hydrogen bond links the peptide molecules into a layer parallel to the ab plane
The title peptide [systematic name: 4-(butan-2-yl)-7,20-bis(1hydroxyethyl)-10,23-bis(propan-2-yl)-12,25-dithia-3,6,9,16,19,22,27,28-octaazatricyclo[22.2.1.1 11,14 ]octacosa-1(26),11(28),13,24(27)-tetraene-2,5,8,15,18,21-hexone acetonitrile monosolvate], C32H48N8O8S2CH3CN, an analogue of ascidiacyclamide (ASC) [cyclo(–Ile–Oxz–D-Val–Thz–)2], lies about a twofold rotation axis, so that the glycine (Gly) and isoleucine (Ile) residues are each disordered over two sites with equal occupancies
The hydroxyl group of Thr (O22) is hydrogen-bonding to the preceding carbonyl group (O16) of Gly or Ile forming 7membered ring. This interaction seems to be caused by 3R-configuration of Cβ atom (C22)

Summary

Akiko Asano and Mitsunobu Doi*

Key indicators: single-crystal X-ray study; T = 200 K; mean (C–C) = 0.007 Å; disorder in main residue; R factor = 0.075; wR factor = 0.213; data-to-parameter ratio = 17.4. The title peptide [systematic name: 4-(butan-2-yl)-7,20-bis(1hydroxyethyl)-10,23-bis(propan-2-yl)-12,25-dithia-3,6,9,16,19,22,27,28-octaazatricyclo[22.2.1.1 11,14 ]octacosa-1(26),11(28),13,24(27)-tetraene-2,5,8,15,18,21-hexone acetonitrile monosolvate], C32H48N8O8S2CH3CN, an analogue of ascidiacyclamide (ASC) [cyclo(–Ile–Oxz–D-Val–Thz–)2], lies about a twofold rotation axis, so that the glycine (Gly) and isoleucine (Ile) residues are each disordered over two sites with equal occupancies. The acetonitrile molecule is located on a twofold axis passing through the C and N atoms. The thiazole rings are faced to each other with a dihedral angle of 9.63 (15) and intramolecular N—H O and O—H O hydrogen bonds are observed. N—H (O,O) hydrogen bond links the peptide molecules into a layer parallel to the ab plane

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Akiko Asano and Mitsunobu Doi