Preparation of 1, 6-Dihydro-3-benzazocines and Related Compounds by Base-Induced Intramolecular Cyclization of 1, 2-Bis (2-isocyano-2-tosylethyl) benzene

Abstract

Treatment of 1, 2-bis (2-isocyano-2-tosylethyl) benzene (5a) with potassium hydroxide in methanol, ethanol, or isopropyl alcohol afforded 2-substituted 1, 6-dihydro-5-isocyano-3-benzazocines (15a-c) by intramolecular cyclization. When tert-butyl alcohol was used as a solvent under the same conditions, 5a was led to 3, 6-dihydro-5-isocyano-3-benzazocin-2 (1H) -one (18) instead of the corresponding benzazocine of type 15d. N-Alkylation of 18 with methyl, ethyl, and isopropyl iodides yielded 3-alkylated 3, 6-dihydro-5-isocyano-3-benzazocin-2 (1H) -ones (20a-c), which are structural isomers of 15a-c.