AbstractFor the performing this research multicomponent reaction of isatin, electron-deficient acetylenic compounds, α-haloketones, ammonium acetate, isothiocyanates and methyl aziridine in aqueous at room temperature was investigated for the production of novel derivatives of azepinothiazine in excellent yields. The synthesized azepinothiazines have OH, NH2 and NH functional groups that have acidic hydrogen and show high antioxidant activity. These synthesized compounds also displayed antimicrobial activity by using the disk diffusion procedure and two Gram-positive and Gram-negative bacteria. Also, to better understanding reaction mechanism density functional theory-based quantum chemical methods have been applied. The employed process for the production of azepinothiazine has some benefits such as short time of reactions, excellent efficiency of the product, easy separation of products.HIGHLIGHTSGreen chemistry is the use of a set of principles to reduce or eliminate the use or generation of unsafe materials in the design, fabrication and applications of chemical products. Among solvents, water is a green solvents and very suitable for performing organic reaction.The present procedure avoids the use of toxic solvent.MCRs open diverse avenues to create novel concatenations in one pot fashion leading to diverse biologically potent heterocyclic scaffolds.Keywords: Azepinothiazinesmulti component reactionalkyl bromideisatinsgram-positive and gram-negative bacteria AcknowledgmentsThe authors gratefully acknowledge the support of Islamic Azad University of Zahedan.Disclosure statementNo potential conflict of interest was reported by the author(s).