Synthesis of 1,2-Dihydroisoquinolines by the Reaction of Isoquinoline with Allyltributyltin or Silyl Enol Ethers in the Presence of N-Acylating Agents

Isoquinolines were allowed to react with allylmbutyltin or silyl en01 ethers in the presence of N-acylating agents to give I-substituted 1,2dihydroisoquinolines in good yields.When a chiral acid chloride was used for an activator, a high diastereoselectivity was observed for the addition.The configuration of a major isomer was elucidated by an X-Ray crystallographic analysis.In the course of our studies on the reaction of unstable N-alkoxycarbonyl quaternary salts of azaaromatics.1 allyltributyltin2 and silyl enol ethers3 are revealed to be good nucleophiles to give N-alkoxycarbonyldihydro adducts in high yields.These results prompted us to investigate its applications to isoquinoline derivatives, which include a variety of bioactive compounds?and it was found that these nucleophiles react with isoquinoline in the presence of chlorofonnate or benzoyl chloride to give I-substituted derivatives.In addition, this 1,2-addition reaction was applied to an asymmetric synthesis, and a chiral acid chloride afforded a 1.2-adduct in a highly diastereoselective manner.Moreover, its absolute configuration was elucidated using an X-Ray crystallographic analysis.This paper describes these results.