| abstract |
A method for preparing d-biotin is disclosed, which comprises condensing (3aR,8aS,8bS)-1,3-dibenzyl-2-oxo-decahydroimidazo[3,4-d]thieno[1,2-a]sulfonium halide with trialkyl methanetricarboxylate in the presence of base to give （3aS, 4S, 6aR）-1,3- dibenzyl -4-(ω,ω,ω-tricarbalkoxy-butyl)- tetrahydro -1 H - thieno[3,4-d]imidazol-2,4(1 H )-one as intermediate, and then subjecting the intermediate to hydrolysis, decarboxylation and ring-closing steps to give d-biotin. |