oxazepinones and thiazepinones correspoding to the formula : ## str1 ## are prepared by mixing an alkali metal salt corresponding to the formula ## str2 ## with oxalyl chloride or bromide in an inert solvent and heating to effect halogenation and fusion , a in the formulas representing a substituted or unsubstituted benzene , naphthalene , or pyridine ring bearing up to two y substituents ; e being oxygen or sulfur ; r being an alkyl , cycloalkyl , or phenalkyl group or a substituted phenalkyl group bearing up to two ar - y substituents ; x being chloro or bromo ; m being an alkali metal ; n being one or two ; and y being a substituent selected from alkyl , alkoxy , trifluorimethyl , nitro , and halo . the products are useful as pharmaceutical intermediates .