N-phenylimide of cis,cis-3-methyl-4-cyclohexene-1,2-dicarboxylic acid;N-phenyl-cis,cis-3-methyl-4-cyclohexene-1,2-dicarboximide;(3aR,4R,7aS)-4-methyl-2-phenyl-3a,4,7,7a-tetrahydroisoindole-1,3-dione
The thiocarbonyl group of monothiomaleimide 1 serves as a more reactive dienophile than the electron-deficient CC double bond in the same molecule for the DielsâAlder reaction with dienes 2câg and provides ortho-endo products 3 exclusively or predominantly over the other possible adducts 4â10.