Boron thiophenoxide

Boron thiophenoxide (6, 409-410) can also be used for this transformation, but requires a temperature of 140° (refluxing xylene). However, this reagent is useful for conversion of a,/3-unsaturated esters to thiolesters. 

The benzene derivatives containing the fluorinated sulfone have been prepared either by nucleophilic substitution of the 4-fluorophenyl derivative (e.g. 1) or by starting with the appropriately substituted sodium thiophenoxide and reacting with perfluoroalkyl iodide follow by oxidation with either MCPBA or chromium oxide (12. li.) The biphenyl derivatives have been prepared by palladium catalyzed cross coupling chemistry of the 4-bromophenyl derivative (e.g. 2) with substituted phenyl boronic acid (yields 37-84%) (JLH, .). Compound 16 has been prepared by palladium catalyzed cross coupling of (4-bromophenyl)perfluorohexyl sulfone with vinyl anisole in 37 % yield (JJL). The vinyl sulfones, 7 and 9, have been prepared by condensation of CH3S02Rf (JJL) with the appropriate aldehyde (yields 70,and 73%) following a literature procedure (1 ). Yields were not optimized. 

DEALKYLATION Boron tribromide. 2-Nitroprop-2-yl hydroperoxide. Pyridine hydrochloride. Sodium thiophenoxide. 

T. Cohen and R. E. Gapinski. The conversion of esters to phenyl thioesters by boron thiophcn-oxide and aluminium thiophenoxide. Tetrahedron Letters, 1978, 4319. 

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