Abstract: The invention discloses a D-biotin preparation method. In the prior art, with a synthesis method utilizing malonic acid diester as raw materials, impurities are also produced along with the obtained D-biotin. The D-biotin preparation method is characterized in that with the presence of dimethyl sulfoxide and inorganic base as catalysts, methane tricarboxylic acid trialkyl ester and (3aR, 8aS, 8bS)-1,3-dibenzyl-2-oxo-10H-iminazole [3,4-d] thiophene [1,2-a] sulfuryl halide are subjected to condensation reaction in methylbenzene solvent to obtain intermediate (3 aS,4S,6aR)-1,3-dibenzyl-4-(?,?,?-3-methoxycarbonylbutyl)-4H-1H-thiophene[3,4-d]iminazol e-2,4(1H)-ketone, and the D-biotin is obtained after the intermediate is treated by the aftertreatment method. By the D-biotin preparation method, production of the impurities is avoided, quality of the biotin is greatly improved on the existing basis, and side reaction is avoided too.

Abstract: Abstract The invention discloses a D-biotin preparation method. In the prior art, with a synthesis method utilizing malonic acid diester as raw materials, impurities are also produced along with the obtained D-biotin. The D-biotin preparation method is characterized in that with the presence of dimethyl sulfoxide and inorganic base as catalysts, methane tricarboxylic acid trialkyl ester and (3aR, 8aS, 8bS)-1,3-dibenzyl-2-oxo-10H-iminazole [3,4-d] thiophene [1,2-a] sulfuryl halide are subjected to condensation reaction in methylbenzene solvent to obtain intermediate (3 aS,4S,6aR)- 1,3 -dibenzyl-4-(?,?,?-3-methoxycarbonylbutyl)-4H- 1H-thiophene[3,4-d]iminazol e-2,4(1H)-ketone, and the D-biotin is obtained after the intermediate is treated by the aftertreatment method. By the D-biotin preparation method, production of the impurities is avoided, quality of the biotin is greatly improved on the existing basis, and side reaction is avoided too.

Abstract: The invention discloses the improved preparation method for D-Biotin. If the composite method takes the malonic acid diester as the raw material, the finial biotin will be generated with impurities. The features of the invention refers to the improved preparation method for D-Biotin includes: firstly, (3aS,4S,6aR)-1,3-dibenzyl-4-(?,?,?-3 -alkoxycarbonyl bytyl)-4H-1H-thiophene[3,4-d]iminazole-2,4(1H)-ketone is got after the methane tricarboxylic acid trialkyl ester and (3aR,8aS,8bS)-1,3-dibenzyl-2-oxo-10H-iminazole[3,4-d]thiophene[1,2-a]sulfuryl halide have the condensation reaction in the alkaline environment and then D-Biotin can be got after the reaction process of hydrolysis, decarboxylation and closed loop. The invention succeeds in greatly improving the biotin quality from the original basis and simultaneously avoids the generation of impurities and the occurrence of side reaction.