O-Silylated steroidal cis-aminoalcohols as chiral auxiliaries: highly diastereoselective Pd-catalyzed cyclopropanation of α,β-unsaturated aldimines

✍ Scribed by M. Dubs; H. Dieks; W. Günther; M. Kötteritzsch; W. Poppitz; B. Schönecker

• Publisher: Elsevier Science
• Year: 2002
• Tongue: French
• Weight: 113 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)00334-9

✦ Synopsis

a,b-Unsaturated imines, obtained from cis-17-silyloxy-16-amino steroids and a,b-unsaturated aldehydes, react with diazomethane in the presence of a catalytic amount of Pd(OAc) 2 with high chemo-and diastereoselectivities to form steroidal cyclopropanocarbaldimines; chromatography on silica gel gives the substituted cyclopropanocarbaldehydes with a high enantiomeric excess and allows recovery of the chiral steroidal auxiliaries.