Abstract
2-a-Naphthoyl- , 2-p-methoxybenzoyl-, 2-p-chlorobenzoyl-, 2-m-nitrobenzoyl-, 2-mesitoyl-, 2-phenylacetyl-, and 2-butyryl-benzoic acids, and benzylidene- and propylidene-phthalides have been subjected to the conditions of the Schmidt reaction to yield, principally, 2-substituted-6-oxo-4:5-benz-1:3-oxazines. Where the substituent is aryl the oxazine can be isolated under the conditions employed; 2-p-methoxyphenyl-, 2-p-chlorophenyl-, 2-m-nitrophenyl-, 2-a-naphthyl, and 2-mesityl-6-oxo-4:5-benz-1:3-oxazines were so obtained. Where the substituent is alkyl or aralkyl the hydrolysis product, an N-substituted-anthranilic acid, is isolated; N-phenylacetyl-and N-butyryl-anthranilic acids were obtained. The mechanism of this reaction, believed to proceed via a cyclic ion, is discussed. Evidence for the existence of a counter-rearrangement, which leads, not to a 2-substituted-6-oxo-4:5-benz-1:3-oxazine or an N-substituted-anthranilic acid, but ultimately, to a primary amine, is given, and the mechanism of the counter-rearrangment is discussed. Experiments concerning the Schmidt reaction of 1:2-benzofluorenone are described. The preparation of 1:2- and 7:8-benzophenanthridines from 9-azido-1:2 -benzofluorene is recorded; the ratio of isomers, 2. 9: 1, is shewn to be in accord with views based on earlier work in the field. A novel method for the preparation of certain 9-azidofluorenes is described. New observations on the acid-catalysed decomposition and the pyrolysis of 9-azido-fluorenes, together with data in the literature, lead to the conclusion that acid-catalysed decomposition of secondary and tertiary azides, also pyrolysis of the latter, yield substituted phenanthridines, but that pyrolysis of secondary azides yields ketimines. The preparation of 2:4-dihydroxyquinoline from 1:3-diketohydrindene, via the Schmidt reaction, has been verified.