A Study on N-Substituted Nortropinone Synthesis using Acetone Equivalents

Abstract

Robinson′s synthesis has long been a classic in organic chemistry due to its simplicity and impact in the industry. Various modifications have been made to improve the system. Among them, replacing acetone with more acidic chemical equivalents such as calcium dicarboxylic acid or ethyl dicarboxylic acetone improved the yield. In line with this trend, our group previously reported the synthesis of mono- and di-N-substituted tropinone derivatives from the one-pot reaction of 2,5-dimethoxy tetrahydrofuran and various amines with acetonedicarboxylic acid in the presence of HCl and water at room temperature. In this study, the synthesis with acetone instead of acetone-dicarboxylic acid was examined. Mono- and di-N-substituted nortropinones were prepared in higher yields in all cases although there were extent to which yields increased depending on the nature of substituents