TETRAHYDRO-1,4-THIAZINE-1,1-DIOXIDES .4. SYNTHESIS AND CONFORMATIONAL-ANALYSIS OF SOME 2,3,5-TRISUBSTITUTED TETRAHYDRO-1,4-THIAZINE-1,1-DIOXIDES

A series of new 2-aroyl-3, 5-diaryltetrahydro-1, 4- thiazine-1, 1-diox ides (2) has been synthesized either from phenacylsulfonylacetic acids (1) or phenacylstyryl sulfones (3), which in turn are obtained from t he substituted acetophenones or styrenes, respectively. Another series of oxycarbonyl-3-aryl-5(4-methyl-phenyl)tetrahydro-l, 4-thiazine-1, 1 -dioxides (5) has been prepared from Z (or E)-alkyl 4-methylstyrylsulf onyl acetates (4). The desired 4 has been obtained from the correspond ing acetylenes or 4-methylstyrene. The structures of 2 and 5 and their preferred chair conformations have been deduced by the analysis of hi gh resolution NMR data supported by correlation spectroscopy.