An original and facile method for the generation of β-naphtha-1-thioquinones using DAST and 2-naphthols has been developed. A series of dehydro-2-naphthol-1-sulphides or naphtha-oxathiane derivatives were synthesized by in situDiels–Alder cycloaddition reactions of β-naphtha-1-thioquinone with itself or various alkenes.
Phthalimidesulfenyl chloride 1 reacts with activated arenes 2a-g, to give monosubstituted derivatives 3a-g. Hydroxysulfenyl compounds 3a-d have been used as suitable source of alpha-oxothiones (ortho-thioquinones) 4a-d, which act as heterodienes in 4+2 cycloaddition reactions.
α-oxosulfines part 2: The first example of Ortho-thioquinone-S-oxides
Benzo-oxathiin-S-oxides 9b and 9c can undergo a Retro Diels-Alder (RDA) reaction to from ortho-thioquinone-S-oxides 12 and 11. These hitherto unknown reactive intermediates can be successfully generated as function of the geometry of the starting sulfoxides and the type of aromatic system involved, and can be trapped as electron poor dienes or dienophiles.