Structure of 4-(n'-pivaloyl)-d(l)-phenylalanyl-d(l)-perhydro-4h-1,4-thiazine-3-(n-methyl) Carboxamide Methanol Monohydrate in the Crystalline State

A crystal of the homochiral isomer of N-Piv-Phe-(γS) Pec-NHMe. CH3OH. H2O is subjected to an X-ray diffraction analysis. C20H29N3O3S. CH3OH. H2O, Mr = 441.58, triclinic, P1, a = 12.981(2), b = 9.939(1), c = 11.345(1) A, α = 75.05(1)°, β = 63.15(1)°, γ = 71.46(1)°. Z = 2, V = 1226.8(3) A3, Dx = 1.20 g. cm−3, CuKα, λ = 1.54178 A, μ = 14.31 cm−1, F (000) = 476, T = 291K, R = 0.058 for 3875 observed reflections. The data reveal a molecular conformation with all trans amide bonds, in an “open form” (ϕ1, ϕ1, ϕ2, ϕ2 = 123.8°, −81.9°, 120.4°, −23.1°) without intramolecular hydrogen bond, stabilized in a crystal environment of strong intermolecular H-bonding.