Structure Of A Fully Protected Seco-Erythronolide B-Acid Derivative

(3S,4R,5S,6R,7R,9R,10S,11S,12S,13S,14R)-14-Benzyloxymethoxy-10,12-O-carbonyl-4-N-imidazolycarbonyl-6,7-O-isopropylidene-3,5,7,9,11,-13-hexamethylhexadec-1-ene-4,6,7,10,12,14-hexol, C38H56N2O9, M(r) = 684.87, monoclinic, P2(1), a = 8.7302 (12), b = 15.597 (2), c = 14.463 (2) angstrom, beta = 104.797 (10)degrees, V = 1904.1 (4) angstrom 3, Z = 2, D(x) (198 K) = 1.19 g cm-3, mu = 0.7893 cm-1, Mo K-alpha radiation, lambda = 0.7107 angstrom, F(000) = 740, T = 198 K, R = 0.0301 for 3141 reflections [F(o) greater-than-or-equal-to 4-sigma(F(o))]. The crystal structure was undertaken to determine the stereochemistry of the title compound. The molecule is folded on itself in such a way that the portion of the molecule from the phenyl ring at C44 and extending to C28 forms nearly a single turn of a right-handed screw. Large deviations from ideality for several Csp3-Csp3 bond angles are observed that are presumably due to intramolecular steric effects. The largest deviations are: C3-C4-C5 117.8 (2), C5-C6-C7 121.2 (2), C7-C8-C9 115.3 (2), C9-C10-C11 116.2 (2), C11-C12-C13 117.2 (2), C14-C15-C16 115.5 (3)degrees.