2,4-Disubstituted furans are prepared by treating 2,3-dibromo-1-phenylsulfonyl-1-propene (DBP, 2) with 1,3-diketones under basic conditions. The furan-forming step involves a deacetylation, and the selectivity of this process depends upon the steric demand of the R group. The substituent in position 4 is elaborated by reaction of sulfonyl carbanions with alkyl halides, acyl halides, and aldehydes. Oxidative or reductive desulfonylation produces the 2,4-disubstituted furans in 60-92% yield. This strategy has been used to prepare rabdoketone A (12) and the naturally occurring nematotoxic furoic acid 13.

A convenient preparation of 2,3-dibromo-1-(phenylsulfonyl)-1-propene (DBP, 1) is available through the one-pot propargylation and oxidation of thiophenol to give the propargyl sulfone 11, which is isomerized and brominated in another one-pot reaction. The new preparation is significantly more scalable, as well as more convenient and robust than the prior art.

Sulfones Q 0600Improved Synthesis of 2,3-Dibromo-1-(phenylsulfonyl)-1-propene (DBP). -The multifunctional title compound is obtained as a mixture of E/Z-isomers (IV)/(V). -(VANZANTEN, A.; MULLAUGH, K.; HARRIGTON, R.; KIEFER, A.; CARLSON, D.; MASTARONE, D.; LIPCHIK, C.; MURPHREE*, S. S.; Synthesis 2004, 16, 2611-2613; Dep. Chem., Allegheny Coll., Meadville, PA 16335, USA; Eng.) -C. Herrmann 16-084