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- imidazolylcarbonyl-6,7-O-isopropylidene-3,5,7,9,11,- 13-hexamethylhexadec-1-ene-4,6,7,10,12,14-hexol, C38H56N2O9, Mr = 684.87, monoclinic, P2(1), a = 8.7302 (12), b = 15.597 (2), c = 14.463 (2) A, beta = 104.797 (10) degrees, V = 1904.1 (4) A3, Z = 2, Dx (198 K) = 1.19 g cm-3, mu = 0.7893 cm-1, Mo K alpha radiation, lambda = 0.7107 A, F(000) = 740, T = 198 K, R = 0.0301 for 3141 reflections [Fo greater than or equal to 4 sigma (Fo)]. 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.