Synthesis of 1,3,8,8a-tetrahydro-3,8-epoxy[1,2-b]isoquinolines and their reactions with oxygen nucleophiles

Abstract

Cycloadditions of 2H-azirines to isobenzofurans is described. The endo and exo products were obtained and were reacted with oxygen nucleophiles. Tetrahydroquinolines or benzofuranols were obtained, usually in excellent yields. Cycloaddition of the less electrophilic azirine (14) was performed at room temperature in the presence of ZnCl2. The cycloadduct was hydrolysed in the reaction conditions, but dehydration to give back the original cycloadduct was obtained in the presence of 4Å molecular sieves. The structure assigned in the literature to the product of hydrolysis of the cycloadduct 10 was rectified.