An ascidiacyclamide diastereomer (No.7)

The natural ascidiacyclamide (ASC) has two Oxz residues having (S,R)-configurations. These chiralities are canged to (S,S) and (R,R). @Aug. 2002

The peptide ring was very flat. Such a structure was the first example of ASC analogues.
Published: Akiko Asano, Takeshi Yamada, Atsushi Numata, Yoshio Katsuya, Masahiro Sasaki, Taizo Taniguchi, Mitsunobu Doi (2002) Biochem. Biophys. Res. Commun. 297, 413-417.
A flat squared conformation of an ascidiacyclamide derivative caused by chiral modification of an oxazoline residue

Drawn by Raster3D with water exclusive surface calculated by MSMS.
Figure shows that No.7 has the cavity of the peptide ring, but ASC not.

X-Ray Data Summary
formulaC36H52N8O6S2, 3(H2O), CH3OH
weight 843.07
space groupP21
Cell Crystal
a 14.4745(4) Ang. description block
b 9.9580(2) Ang. colour Colorless
c 15.3414(4) Ang. size (mm) 0.06x0.04x0.04
alpha 90 deg. Dx (g/ml) 1.271
beta 94.859(2) deg. F(000) 904
gamma 90 deg. mu 0.182
volume 2203.32(9) Ang^3 wavelength (A)0.836
Z 2
Diffrn measurementRefinementspace
device type Rigaku R-AXIS IV Flack 0.02(12)
Rint parameters 515
T 100 K restraints 0
theta max (deg.) 30.0 R_factor_gt 0.536
total reflections4543 wR_factor_gt 0.1349
reflections(obs) 4423 .gt. 2sigma(I) dela rho_max 0.555 e A^3
Structurespace space space space space space delta rho_min -0.627 e A^3
solution SHELXS-97 shift/su_maxlt.0.001
refinementSHELXL-97 Goodness of fit 1.136

Data collection was performed on a synchrtoron, SPring-8 BL24XU (C00B24XU-5003N).
Get PDB coordinates
Appendix: 1H-NMR chart of ASC7 (TIFF, 104KB), Get PDB coordinates of dASC7,
1H-NMR chart of dASC7 (TIFF, 108KB)
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