SYNTHESIS OF THE TETRAHYDROOXAZOLO[2,3-B][3]BENZAZEPIN-3(2H)-ONE SYSTEM AND X-RAY CRYSTAL-STRUCTURE OF AN 11A-ETHOXY DERIVATIVE

Photolysis of the N-chloroacetyl imide derivative 3-chloroacetyl-7,8-d imethoxy-4,5-dihydro-1H-3- benzazepin-2(3H)-one (2) in aqueous acetoni trile gave 1a-tetrahydrooxazolo[2,3-b][3]benzazepin-3(2H)-one (4) in 8 1% yield. This representative of a new heterocyclic system could be co nverted into the 11a-ethoxy derivative (5) by recrystallization from e thanol. The structure of (5) was confirmed by a room-temperature singl e-crystal X-ray study. Crystals are monoclinic, Cc, a 17.623(9), b 7.5 50(4), c 12.872(3) Angstrom, beta 112.55(4)degrees, Z = 4; conventiona l R on \F\ was 0.034 for 1072 'observed' (I > 3 sigma(I)) reflections.