Convenient Au(III)-Catalysed Synthesis of 1-Alkyl-3-diethoxy-phosphoryl-1,2,3,4-tetrahydroisoquinolines

Abstract

We report here convenient approach to the synthesis of 1-alkyl-3-diethoxyphosphoryl-1,2,3,4-tetrahydroisoquinolines through cyclization of alkynylsubstituted α-aminophosphonates in the presence of AuCl3 with following reduction by NaBH4. Starting alkynylsubstituted α-aminophosphonates were easily synthesized by using Sonogashira reaction of diethyl (1-((diphenylmethylene)-amino)-2-(2-iodophenyl)ethyl)phosphonate with series of terminal alkynes. The 1-alkyl-3-diethoxyphosphoryl-1,2,3,4-tetrahydroisoquinolines with different alkyl substituents were obtained as two enantiomers with cis-configuration in good yields.