A Facile Synthesis of Oxoindenothiazine and Dioxospiro(indene‐2,4′‐thiazine) Derivatives from (Substituted ethylidene)hydrazinecarbothioamides

( E )‐2‐[2‐(1‐Substituted ethylidene)hydrazinyl]‐5‐oxo‐9b‐hydroxy‐5,9b‐dihydroindeno[1,2‐ d ][1,3]‐thiazine‐4‐carbonitriles and ( E )‐5‐oxo‐[( E )‐(1‐substituted ethylidene)hydrazinyl]‐2,5‐dihydroindeno[1,2‐ d ][1,3]thiazine‐4‐carbonitriles have been obtained from the reaction of 2‐(substituted ethylidene)hydrazinecarbothioamides with 2‐(1,3‐dioxo‐2,3‐dihydro‐1 H ‐inden‐2‐ylidene)propanedinitrile ( 1 ) in ethyl acetate solution. However, ( Z )‐6′‐amino‐1,3‐dioxo‐3′‐substituted‐2′‐[( E )‐(1‐phenylethylidene)hydrazono]‐1,2′,3,3′‐tetrahydrospiro(indene‐2,4′‐[1,3]thiazine)‐5′‐carbonitriles were observed during the reaction of N ‐substituted‐2‐(1‐phenylethylidene)hydrazinecarbothioamides with ( 1 ). The structure assignment of products has been confirmed on the basis of 1 H‐, 13 C‐NMR, and mass spectrometry , as well as theoretical calculations.