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An efficient and highly stereoselective synthetic procedure is reported for the construction of symmetrical and unsymmetrical (E)-polymethoxystilbene and (E)-polyhydroxystilbene derivatives. The strategy rests on a cross-metathesis reaction catalyzed by stable, well-defined (alkylidene)ruthenium complexes, in particular the second-generation Grubbs catalyst [RuCl 2 (=CHPh)(SIMes)(PCy 3 )] [SIMes = 1,3-

Polyphenylalkene derivatives Q 0740Stereoselective Synthesis of (E)-Hydroxystilbenoids by Ruthenium-Catalyzed Cross-Metathesis. -By use of Grubbs second-generation catalyst, symmetrical and unsymmetrical polyhydroxystilbene derivatives are obtained in high yields and excellent (E)-selectivity. The selectivity towards mixed-coupling products can be enhanced by excess of one coupling partner. Thus, resveratrol (III) is prepared in 86% isolated yield by reaction of a ten-fold excess of styrene (Ia) with analogue (Ib), while the formation of stilbene (IIa) is totally suppressed. -(FERRE-FILMON, K.; DELAUDE, L.; DEMONCEAU, A.; NOELS*, A. F.; Eur. J. Org. Chem. 2005, 15, 3319-3325; Cent. Educ. Res. Macromol., Univ. Liege, B-4000 Liege, Belg.; Eng.) -Klein 47-092