Synthesis of the Tetrahydrooxazolo[2,3-b][3]benzazepin-3(2H)-one System and X-Ray Crystal Structure of an 11a-Ethoxy Derivative

Abstract

Photolysis of the N-chloroacetyl imide derivative 3-chloroacetyl-7,8-dimethoxy-4,5-dihydro-1H-3-benzazepin-2(3H)-one (2) in aqueous acetonitrile gave 11a-hydroxy-8,9-dimethoxy-5,6,11,11a-tetrahydro-oxazolo[2,3-b][3]benzazepin-3(2H)-one (4) in 81% yield. This representative of a new heterocyclic system could be converted into the 11a-ethoxy derivative (5) by recrystallization from ethanol. The structure of (5) was confirmed by a room-temperature single-crystal X-ray study. Crystals are monoclinic, Cc, a 17·623(9), b 7·550(4), c 12·872(3) Å, β 112·55(4)°, Z = 4; conventional R on F was 0·034 for 1072 ‘observed’ (I > 3σ(I)) reflections.