Diastereoselective Synthesis of γ- and δ-Lactams from Imines and Sulfone-Substituted Anhydrides
摘要:
Sulfone-substituted gamma- and delta-lactams have been prepared in a single step with high diastereoselectivity. Sulfonylglutaric anhydrides produce intermediates that readily decarboxylate to provide delta-lactams with high diastereoselectivity. Substituents at the 3- or 4-position of the glutaric anhydride induce high levels of stereocontrol. Sulfonylsuccinic anhydrides produce intermediate carboxylic acids that can be trapped as methyl esters or allowed to decarboxylate under mild conditions. This method has been applied to a short synthesis of the pyrrolizidine alkaloid (+/-)-isoretronecanol.
Hydrogenation of pyrrolizin-3-ones; new routes to pyrrolizidines
作者:Xavier L. M. Despinoy、Hamish McNab
DOI:10.1039/b910199c
日期:——
catalysts. Good diastereoselectivity (up to >97:3, depending on catalysts and solvent) can be achieved if the pyrrolizin-3-one is substituted at the 1- (or 7-) position(s), but the selectivity is reduced if both positions are substituted. Subsequent deoxygenation of the pyrrolizidin-3-ones provides concise, diastereoselectiveroutes to the necine bases (±)-heliotridane 5, (±)-isoretronecanol 6 and (±)retronecanol