Ortho thioquinone

Phenols79 react with phthalimidesulphenylchloride (PhthNSCl) to yield N-thiophthalimides. These when treated with tertiary amines afford unstable ortho-thioquinones. Base-catalysed CN-elimination from camphoryl thiocyanate yields the a n -l,3-dithietane as the sole stereoisomer via thioketone80 (Scheme 9). 

Ortho-thioquinones are also accessible by this route [238, 239]. They were treated with glycals as dienophiles with success (Table 5, entry 2). These reactions were designed [240] to offer an original glycosyl transfer, by achieving a Diels-Alder reaction with the appropriate a,adioxothione (Table 5, entry 4), and a simple Raney nickel reductive desulfurisation of the cycloadduct. 

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