Abstract: A modified stereospecific total synthesis of d-biotin from L-(+)-cysteine based on Confalone’ s method was described, Witting-Schlosser olefination of the aldehyde(5) with Witting reagent derived from carbomethoxypropyl-triphenylphosphonium bromide ,after acidic work-up,furnished transolefin(6 ) stereospecifically in 72% yield.Treatment of the bromolactam(9) with azidotrimethylsilane instead of lithium azide via SN2 nucleophilic substitution increased the yield of cis azido lactam(10).The overall yield of d-biotin was 3.7%from cysteine.