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Irradiation of substituted arylazirines produces nitrile ylides which react with methanol to give methoxyimines in excellent yield. Deuterium labeling studies indicate that the electron density is highest on the disubstituted carbon atom of the nitrile ylide formed on irradiation. With this conclusion, all of the regiochemical data found in the photoaddition of arylazirines with electron-deficient dipolarophiles can be explained by use of the frontier orbital method. The addition of alcohol to nitrile ylides was also found to occur intramolecularly. A new synthesis of cycloalkanones was devised and is based upon the photolysis of spiroazirines in alcohol followed by aqueous hydrolysis. Irradiation of 2-phenyl-1 -azaspiro[2.2]pent-1ene in methanol however, resulted in a Griffin-type fragmentation and produces ethylene and 2-phenylazirinylidene. This novel carbene reacts with methanol to produce 2-methoxy-2-phenyl-2//-azirine (33). On further photolysis, azirine 33 undergoes C-C bond cleavage to produce a nitrile ylide which can be trapped by methanol or by an added dipolarophile such as methyl trifluoroacetate. When the irradiation of azaspiro[2.2]pentene is carried out in the presence of oxygen, benzonitrile and carbon monoxide are formed. The formation of these products can best be explained by invoking 2-phenylazirinone as a transient intermediate.

Azetidine carboxylic acids or esters have been converted to /3-lactams by three types of oxidative decarboxylation. The procedures involve (a) dianion oxygenation followed by decomposition of the -hydroperoxy carboxylic acid, (b) addition of a peracid to the iminium salt formed from the acid chloride, followed by pyridine-promoted /3 elimination, and (c) cleavage by singlet oxygen of the enamino ketene acetal formed by enol silylation.

high-resolution mass spectrum, caled for C9H15N03 m/e 185.1047, found m/e 185.1049.Ethyl a-Isopropyl-2-oxo-l-azetidineacetate (21b). By the above procedure, 285 mg of JV-(2,2-dimethyl-l-carbethoxyethyl)-2-(carbo-tert-butoxy)azetidine (3t) was converted to 121 mg (61%) of ethyl a-isopropyl-2-oxo-l-azetidineacetate (21b) identical with an authentic sample.36