A successful acid promoted asymmetric pictet-spengler reaction of Na-BOC protected tryptophans. Effect of the BOC group on reactivity and stereoselectivity
作者:Puwen Zhang、James M. Cook
DOI:10.1016/0040-4039(95)01448-q
日期:1995.9
N-a-BOC protected tryptophans 1 and 2 successfully undergo the Pictet-Spengler cyclization with a series of aldehydes in the presence of an acid catalyst (p-TSA) to furnish a mixture of trans and cis 1,2,3,4-tetrahydro-beta-carbolines (3 and 4). During removal of the BOC function with TFA, the mixture of trans (3) and cis (4) isomers was enantiospecifically converted into the trans N-a-H 1,2,3,4-tetrahydro-beta-carboline 5, a key intermediate for the construction of N-a-H substituted sarpagine alkaloids.