Synthetic approaches to 2‐substituted 1‐oxo‐ and 3‐oxotetrahydroisoquinolines

Abstract

Abstract 2‐Substituted homophthalimides 2a‐c were reduced regioselectively with sodium borobydride to carbinol‐lactam intermediates 3a‐c , which were dehydrated, followed by hydrogenation, to give 1‐oxo‐tetrabydroisoquinolines or 3,4‐dihydroisoquinolin‐1(2 H )ones 5a‐c . The isomeric 3‐oxo‐tetrahydro‐isoquinolines or 1,4‐dihydroisoquinolin‐3(2 H )‐ones 8a‐i were obtained in satisfactory yields via heating 3‐isochromanone ( 6 ) with the corresponding amines 7a‐i in the presence of aluminum chloride.