Total Syntheses of (−) Epilupinine and (−)-Tashiromine Using Imino-Aldol Reactions
摘要:
Short routes to enantiomerically pure indolizidine and quinolizidine alkaloids have been developed using imino-aldol reactions of enolates derived from phenyl 5-chlorovalerate. High levels of syn selectivity (dr similar to 13-16:1) were obtained using lithium enolates of phenyl esters In combination with tert-butylsulfinyl imines. The imino-aldol adducts were deprotected and cyclized to afford (-)-epilupinine ((-)-2) and (-)-tashiromine ((-)-1) in two further steps.