Thermal cycloaddition reactions of thiocarbonyl compounds. Part 3. A novel [4 + 2] cycloaddition reaction of thiocarbonyl compounds with o-quinone methanides

Abstract

Thermal cycloaddition reactions of adamantanethione (3) and thiobenzophenone (8a) with o-quinone methanides such as the o-benzoquinone methanides (2a–g) and o-naphthoquinone methanides (2h–j) occurred smoothly at 180–200 °C to afford, regioselectively, the adamantane-2-spiro-2′-[1,3]benzoxathiines (4a–g), the naphth[1,3]oxathiines (4a–g), and the naphty[1,3]oxathiines(4h–j), and the 2,2-diphenyl-1,3-benzoxathiines (9a) and (9g), all novel [4 + 2] cycloadducts, in good yields.