O-Benzoylhydroxamates

Primary amines RNH2, where R is a primary alkyl group such as Pr, benzyl or allyl, are oxidized to O-benzoylhydroxamic acids RNHOBz by benzoyl peroxide239. 

In synthetic work, amidyl radicals, prepared by BusSnH/AIBN-mediated homolysis of O-benzoylhydroxamic acid derivatives, have been shown to cyclize in a A-exo fashion to give -lactams (Scheme 10). In addition, radicals generated in this way have also been reported to undergo 5-exo cyclization to give mixtures of cis- and Iranx-pyrrolidinones with the steric nature of the Al-substituent having little effect on the stereochemical outcome (Scheme 11). The major products detected were those predicted by application of the Beckwith rule. ... 

O-Benzoylhydroxamates. Primary amines are converted to RN(OBz)COR by reaction with BzOOBz in dichloromethane at pH 10.5 (buffer) and further A -acylation. 

Changing the base to triethylamine improves the yield of benzoylhydroxamic acid (96a) up to 91% the purification required column chromatography. Independently of the substituent in both Af-acylbenzotriazole and hydroxylamine, the desired O-alkyl, N-alkyl and 0,A-dialkyl hydroxamic acids were obtained as sole products as a result of nucleophilic displacement of the benzotriazolyl moiety by the hydroxylamine nitrogen. 

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