The Preparation of Nonracemic Secondary α-(Carbamoyloxy)alkylzinc and Copper Reagents. A Versatile Approach to Enantioenriched Alcohols
摘要:
GRAPHICSChiral alpha-(carbamoyloxy)alkyllithium reagents, prepared using Hoppe's sBuLi/(-)-sparteine methodology, were transmetalated with ZnCl2. Further transmetalation with CuCN with overall retention of configuration gave chiral species that reacted with various electrophiles to give enantiomerically pure alcohols after deprotection. A short, highly efficient synthesis of an industrially relevant pheromone, japonilure, illustrates the value of the methodology.
A process for the preparation of a compound of the formula ##STR1## which comprises deprotonating a carbamate of the formula ##STR2## in an inert solvent with a selective base, in the presence of a chelate-forming diamine to give a compound of the formula ##STR3## and then reacting III in an inert solvent, either with an achiral electrophile of the formula (IV) or (V) or with an optionally prochiral electrophile of the formula (VI) ##STR4## and in the case in which R.sup.1 represents an electrofugic leaving group, optionally again electrophilically substituted with the formation of an acyl anion and renewed deprotonation, and in a last step, solvolytically removing the protecting group --CO--NR.sup.10 R.sup.11.
The Preparation of Nonracemic Secondary α-(Carbamoyloxy)alkylzinc and Copper Reagents. A Versatile Approach to Enantioenriched Alcohols
作者:Julien P. N. Papillon、Richard J. K. Taylor
DOI:10.1021/ol016986e
日期:2002.1.1
GRAPHICSChiral alpha-(carbamoyloxy)alkyllithium reagents, prepared using Hoppe's sBuLi/(-)-sparteine methodology, were transmetalated with ZnCl2. Further transmetalation with CuCN with overall retention of configuration gave chiral species that reacted with various electrophiles to give enantiomerically pure alcohols after deprotection. A short, highly efficient synthesis of an industrially relevant pheromone, japonilure, illustrates the value of the methodology.