Studies on tetrahydroisoquinolines. Part 14. A synthesis of 4-alkoxyaporphines

Abstract

(±)-4β-Acetoxythaliporphine (2) on dissolution in methanol is converted into (±)-4β-methoxyaporphine (4). While (2) reacted with primary alcohols (ethyl and benzyl alcohols) in the presence of boron trifluoride-ether to give the corresponding (±)-4β-alkoxythaliporphines (7) and (8) stereospecifically, reaction with secondary alcohols (isopropyl alcohol and cyclohexanol) and with neopentyl alcohol gave a mixture of the (±)-4β-(11), (12), and (14) and (±)-4β-(9), (10), and (13) alkoxyaporphines. However, in the case of reaction with t-butyl alcohol several (±)-4-alkenyl derivatives (15), (16), (19), and (21)–(23) were obtained.