title: Substrate Controlled Synthesis of Benzisoxazole and Benzisothiazole Derivatives via PhI(OAc)2-Mediated Oxidation Followed by Intramolecular Oxidative O-N/S-N Bond Formation.
abstract: A phenyliodine(III) diacetate (PIDA)-mediated, highly efficient and tandem approach for the synthesis of aryldiazenylisoxazolo(isothiazolo)arenes from simple 2-amino-N'-arylbenzohydrazides has been developed. The reaction proceeds via formation of (E)-(2-aminoaryl)(aryldiazenyl)methanone as the key intermediate, followed by intramolecular oxidative O-N/S-N bond formation in one pot at room temperature. The quiet different reactivity of the substrate is due to the formation of a diazo intermediate which encounters a nucleophilic attack by carbonyl oxygen on the electrophilic amine to produce isoxazole products, as compared to the previous reportsa,b,4 in which an N-acylnitrenium ion intermediate is intramolecularly trapped by an amine group.
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute , Lucknow-226031, India.
authors.forename: Devireddy
authors.initials: D
authors.lastname: Anand
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute , Lucknow-226031, India.
authors.forename: Om P S
authors.initials: OP
authors.lastname: Patel
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute , Lucknow-226031, India.
authors.forename: Rahul K
authors.initials: RK
authors.lastname: Maurya
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute , Lucknow-226031, India.
authors.forename: Ruchir
authors.initials: R
authors.lastname: Kant
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute , Lucknow-226031, India.
authors.forename: Prem P
authors.initials: PP
authors.lastname: Yadav