The improved synthesis,Diels‐Alder reactions,and desulfuration of trithio‐1,8‐naphthalic anhydride

In the presence of a strong Lewis base, such as Et₃N, trithio‐1,8‐naphthalic anhydride (3) is easily oxidized. Two improved syntheses of trithio‐1,8‐naphthalic anhydride (3) are described. Trithio‐1,8‐naphthalic anhydride (3) undergoes Diels‐Alder reactions with electron‐deficient alkenes to give novel fused heterocyclic compounds (6–11) that then can undergo a novel, gradual desulfuration dimerization with triethyl phosphite to afford 12 and its analogs 13 and 14. The structures of 6–14 are confirmed by microanalysis, IR, and NMR spectroscopy, and MS. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 141–146, 1999