3-Ethyl-2,4-dimethyl-1,5-benzodiazepine

Dimethyl-1,5-benzodiazepine, formulated as its 3H tautomer (445), underwent vapor-phase pyrolysis (850°C, 0.02 mmHg, 15 min) to give a mixmre from which three quinoxalines were isolated 2,3-dimethyl- (446, R = Me) (7%), 2-ethyl-3-methyl- (446, R = Et) (10%), and 2-methyl-3-vinylquinoxa-line (447) (1%). ... 

A solution of 0.7 g of 2-(2-amino-N-methylacetamido)-5-chlorobenzophenone in 10 ml of a 50% solution (by weight) of diketene in acetone is refluxed for 3 hours and then evaporated to give a brown oil. The oil is chromatographed on 200 g of silica gel using a 1 1 (by volume) mixture of ethyl acetate cyclohexane 25 ml fractions are collected. Fractions 11-14 are combined, mixed with chloroform, evaporated and triturated with ether to give 0.337 g of ll-chloro-8,12b-dihydro-2,8-dimethyl-12b-phenyl-4H-[l,3]oxazino[3,2-d] [1.4] benzodiazepine-4,7(6H)-dione as a pale yellow solid, MP 174°C to 176°C. 

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