Facile and Short-Step Synthesis of 5-Substituted 2,3,4,5-Tetrahydrobenz[f][1,4]Oxazepines Using a Modified Pictet-spengler Reaction
作者:Yoshie Horiguchi、Toshiaki Saitoh、Michikazu Kitabatake、Takuya Sugimoto、Hiromu Kawakubo、Kunihiko Mohri
DOI:10.3987/com-16-13632
日期:——
5-Substituted 2,3,4,5-tetrahydrobenzo [1,4] oxazepines (6) were synthesized using a modified Pictet-Spengler reaction of formyliminium ion (4) as the key step. Cyclization of 4 proceeded readily by using trifluoroacetic acid as a catalyst, giving 5 -substituted N-formyl-2,3,4,5-tetrahydrobenzo[f][1,4]oxazepines (5) in 26-78% yield. The imination of 2-phenoxyethanamine (1) with aldehydes, formylation of the resulting imines (3), and the acid-catalyzed cyclization steps could be carried out in a one-pot procedure. Hydrolysis of 5 with hydrochloric acid gave the 5-substituted 2,3,4,5-tetrahydrobenzo[f][1,4]oxazepines (6) in high yields.