Structure of (2S)-1-[(2R)-2,4-diphenyl-4-oxobutylideneamino]-2-(methoxymethyl) pyrrolidine

Preliminary Weissenberg photographs, showed that crystals of the title compound (C22H26N2O2), belonged to the orthorhombic system with systematic absence consistent with the space group P2 up arrow 2(1)2(1). The unit-cell dimensions and their standard deviation, obtained at room temperature (293 K) were a = 10.583(6) Angstrom, b = 18.812(2) Angstrom, c = 9.962(1) Angstrom, Z = 4. The unit cell volume (V) was 1983(1) Angstrom(3) and the absorption coefficient (mu) was 0.075 mm(-1), D-c was 1.174 and D-m measured by flotation was 1.18 Mgm(-3); F(000) = 752, lambda (MoKalpha) = 0.7107 Angstrom. The structure was solved by direct methods and refilled by full-matrix least squares methods to a final R(F) = 0.041 and Rw(F-2) = 0.12. This work unambiguously establishes the overall conformation of the title molecule auld the configuration for the new chiral centre C2 is R. The pyrrolidine ring adopts a perfect envelope E-2 conformation. Crystal cohesion is only governed by van der Waals contacts.