Sensibilisierte Photooxidation von Butadien-(1,3)-sultamen-(1,4)

Sensitized Photooxidation of Butadiene-(1,3)-sultames-(1,4) The sensitized photooxidation of the butadiene-sultames 1a–d gives 2-aryl-3,5-dimethyl-5-hydroxy-1,1,6-trioxo-5,6-dihydro-2H-1,2-thiazines 2a–d in yields of 60%. The compounds 2a–d are instable against bases and acids. With triethylamine the N-aryl-5-hydroxypyrrolin-2-ones 5a–d are formed by SO₂-extrusion. With alkali 2b reacts to 5b and cis-β-acetyl-methacrylic acid 4 . ¹H- and ¹³C-n.m.r. spectroscopic data of 2 and 5 are given.