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

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(2H)ones 5a‐c. The isomeric 3‐oxo‐tetrahydro‐isoquinolines or 1,4‐dihydroisoquinolin‐3(2H)‐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.