Bisulfenylation

Sulfenylation of active methylene compounds. Sulfenylation of active methylene compounds by the sulfenyl transfer reagents 1 ordinarily gives a mixture of mono-and bisulfenylated products in which the latter predominate.1 However, the bisulfenylated products are reduced cleanly by sodium thioethoxide to monosulf-enylated products.2... 

Trost also found that treatment of these cyclobutanones with sodium methoxide and diphenyl disulfide leads to in situ bisulfenylation and ring cleavage (secosulfenylation). This was applied to the total synthesis of verrucarol, a complex tetrahydrochromanone substituted at the ring junction by a hydroxymethyl substituent. The synthetic strategy twice used the cyclobutanone formation from 1-lithiocyclo-propyl phenyl sulfide and a ketone, followed by the secosulfenylation process and Baeyer-Villiger type rearrangement of cyclobutanone. Only this part of the synthesis is described in Scheme 28. 

Treatment of the titanium complex (149) with two equivalents of bisulfenyl chloride afforded the bicyclic compound (150) (mp 204°C dec.) in 30-40% yield (Scheme 13) <9lCB214l>. Reaction of (149) with SCI2 and S2C12 gave (151) and (152) in 40% total yield in a ratio of 1 1 (Scheme 13)... 

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