Gi. Georg et al., AN EFFICIENT SEMISYNTHESIS OF TAXOL FROM [(T-BUTYLDIMETHYLSILYL)OXY]-4-PHENYL-2-AZETIDINONE AND 7-(TRIETHYLSILYL)BACCATIN III, Bioorganic & medicinal chemistry letters, 3(11), 1993, pp. 2467-2470
An investigation of the ester enolate-imine cyclocondensation demonstr
ated that (-)-10-dicyclohexylsulfamoyl-D-isoborneol is an excellent ch
iral auxiliary for the formation of [(t-butyldimethylsilyl)oxy]-4-phen
yl-2-azetidinone in high enantiomeric purity. Coupling between [(t-but
yldimethylsilyl)oxy]-4-phenyl-2-azetidinone and 7-(triethylsilyl)bacca
tin III in the presence of sodium hydride as the base provided an effi
cient taxol semisynthesis.