Asymmetric construction of two contiguous stereocenters by diastereoface differentiating addition reaction of thiols to chiral imides: Formal synthesis of (+)-diltiazem
摘要:
A high degree of diastereoselectivity has been achieved on the asymmetric construction of two contiguous stereocenters by the conjugate addition of thiols to alpha,beta-unsaturated imides possessing Evans's chiral auxiliary. Addition reactions of thiophenol to chiral E- and Z-2-methylcrotonyl imides 4 proceeded with high diastereoface selectivities. Diastereoselectivities were discussed when E- and Z-imides 4 and 5 were used as the substrates. A successful application was demonstrated by the formal synthesis of a clinically useful cardiac drug, (+)-diltiazem. (C) 1997, Elsevier Science Ltd.
Novel 7-azido-3-cephem compounds are prepared via .alpha.-amino-phosphonoacetate esters. The cephem compounds are intermediates for the preparation of novel and known useful antibiotic cephalosporins.
Asymmetric construction of two contiguous stereocenters by diastereoface differentiating addition reaction of thiols to chiral imides: Formal synthesis of (+)-diltiazem
A high degree of diastereoselectivity has been achieved on the asymmetric construction of two contiguous stereocenters by the conjugate addition of thiols to alpha,beta-unsaturated imides possessing Evans's chiral auxiliary. Addition reactions of thiophenol to chiral E- and Z-2-methylcrotonyl imides 4 proceeded with high diastereoface selectivities. Diastereoselectivities were discussed when E- and Z-imides 4 and 5 were used as the substrates. A successful application was demonstrated by the formal synthesis of a clinically useful cardiac drug, (+)-diltiazem. (C) 1997, Elsevier Science Ltd.