Synthesis of (3aS,6aR)-1,3-Dibenzyl-tetrahydro-1H- thieno[3,4-d]-imidazole-2(3H)-one-4-ylidenepentanoic Acid and Characterization of Its Crystal

The intermediate of d-biotin, (3aS,6aR)-1,3-dibenzyltetrahydro-1H-thieno[3,4- d]-imidazole-2(3H)-one-4-ylidenepentanoil acid was synthesized from (3aS,6aR)-1,3-dibenzylte- trahyro-4H-thieno[3,4-d]-imidazole-2,4(1H)-dione by using the Grignard reaction. The structure of 3 was characterized by IR, 1H NMR and MS, and the absolute configuration was further confirmed by X-ray crystal structure analysis. Compound 3 crystallizes in monoclinic, space group P21 with a = 11.030(2), b = 7.783(2), c = 12.797(2) , b = 93.44(1)o, Z = 2, Mr = 422.53 (C24H26N2O3S), V = 1096.3(6) 3, = 0.177 mm-1, Dc = 1.280 g/cm3, F(000) = 448 and T = 293(2) K. The final R = 0.0737 and Rw = 0.1974 for 1009 observed reflections with I >2s(I).