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A novel simple and efficient synthesis of biaryls via a Pd-catalyzed decarboxylative cross-coupling reaction of arenecarboxylic acids and diaryliodonium triflates is described. The PdCl2/DPEphos catalytic system in the presence of Ag2CO3 in DMSO was found to be the most efficient. Various biaryls, including sterically hindered biaryls, were synthesized with yields ranging from 37 to 85%.

A simple route to diaryl sulfides using a decarboxylative palladium-catalyzed reaction between electron-rich 2,6-dialkoxybenzoic acid derivatives and diaryl disulfides is reported. This coupling proceeds efficiently in the presence of Pd(CF(3)CO(2))(2) and Ag(2)CO(3) in a 65:1 mixture of 1,4-dioxane and tetramethylene sulfoxide (TMSO). We present also the first formation of a carbon-selenium bond via a palladium-catalyzed decarboxylative cross-coupling.

Syntheses of air- and moisture-stable heterogeneous (tert-butylarylphosphino)polystyrene-supported Pd catalysts and their use for versatile Suzuki-Miyaura reactions of aryl chlorides and arylboronic acids under non-anhydrous conditions are reported. The catalysts are easily recovered by filtration. They can be used many times (more than seven) without showing any loss of activity, and the amount of Pd leached is extremely low (<0.1%).

3c is the most active catalyst for Heck reactions. The couplings are performed under non-anhydrous reaction conditions and require only low amounts of supported palladium (0.5 mequivs. for Suzuki-Miyaura, 1.0 mequiv. for Sonogashira and 0.5 mequivs. for Heck reactions could be sufficient). Catalysts 3a-j are recovered by filtration and can be reused more than four times with no loss of efficiency.

The 'naked sugar' (+)-(1R,2R,4R)-2-endo-cyano-7-oxabicyclo[2.2.l]hept-5-en-2-exo-yl acetate ((+)-4) was converted (7 steps, 45 % overall) with high stereoselectivity into (-)-(4R,5S,6R)-4,5,6-tris{[(tert-butyl)dimethylsilyl]oxy}cyclohex-2-en-l-one ((-)-11). Reduction of (-)-11 with NaBH4.CeC1,.7 H,O, followed by deprotection of the silyl ether moieties gave (+)-conduritol F ((+)-1; 47 %) whose characteristics were identical to those of natural (+)-leucanthemitol. Reduction of (-)-I1 with DIBAH, followed by deprotection of the silyl ether moiety led to (-)-conduritol B ((-)-3; 51 %).