Photochemical induced cis–trans-isomerization of substituted α-(4H-3,1-benzothiazin-4-ylidene) ketones and esters

Abstract

A series of α-(4H-3,1-benzothiazin-4-ylidene) ketones has been prepared and their photochemistry studied. The normal cis-form is converted into the trans-form on irradiation of ethanolic solutions. The photoproducts revert to starting materials by a thermal process which obeys first-order kinetics. The rate constants are slightly affected by variation of substituents on the benzothiazine nucleus.