A novel and efficient iodine(III)-mediated access to 1,4-benzodiazepin-2-ones

A novel access to 1,4-benzodiazepin-2-ones starting from glycine and alanine derivatives is described. The key cyclization step was performed by the action of phenyliodine(III)bis(trifluoroacetate) (PIFA) on the corresponding methoxyamide derivatives leading to the C(9a)N(1) bond construction. This strategy avoids the necessity of additional functionalization on the phenyl ring and facilitates the access to a number of 1,4-benzodiazepine derivatives. Additionally, no racemization in the cyclization step was observed starting from optically pure (S)-alanine ester.