Joucla, Lionel Cusati, Giuseppe Pinel, Catherine Djakovitch, LaurentThe synthesis of (E)-stilbenes was performed following a one-pot Suzuki/Heck sequence through the use of potassium vinyltrifluoroborate. The combination of heterogeneous palladium/silica (Pd/SiO2) catalyst with potassium phosphate monohydrate (K3PO4H2O) as base resulted in useful to good isolated yields regardless of the ortho-, meta- or para-substitution of the aryl halides employed. In a sustainable approach. we found that bio-sourced 1,3-propanediol could advantageously replace N-methyl-pyrrolidone (NMP) as similar yields were obtained Moreover, the reactivity gap between aryl iodides and bromides resulting from the use of 1,3-propanediol allowed an efficient multi-component approach toward the synthesis of (E)-stilbenes. Furthermore. this heterogeneous catalyst was found to he extremely robust despite the use of aerobic conditions and was successfully re-used over several cycles
Polyphenylalkane derivatives Q 0720Efficient Heterogeneously Palladium-Catalyzed Synthesis of Stilbenes and Bibenzyls. -The one-pot synthesis of bibenzyls (IV) is conducted by the Heck cross-coupling reaction between aryl bromides (I) and styrenes (II) followed by hydrogenation of the resulting stilbenes (III). In general, good to high yields are achieved for both the stilbenes and the bibenzyls. Some limitations of the procedure are observed when strongly deactivated aryl bromides are applied. This disappointing result can be circumvented to some extent by using the corresponding iodo derivatives. -(CUSATI, G.; WEDIG, A.; DJAKOVITCH*, L.; Lett. Org. Chem. 6 (2009) 1, 77-81; Inst. Rech. Catal. Environ., CNRS, Univ. Claude Bernard Lyon, F-69626 Villeurbanne, Fr.; Eng.) -H. Hoennerscheid 23-094
Indole derivatives R 0140First Heterogeneously Palladium-Catalyzed Fully Selective C3-Arylation of Free NH-Indoles. -The optimized conditions allow a simple preparation of a series of title compounds. The yields strongly depend on the nature of the substituent at position 2 of the indole nucleus. -(CUSATI, G.; DJAKOVITCH*, L.; Tetrahedron Lett. 49 (2008) 16, 2499-2502; Inst. Rech. Catal. Environ., CNRS, Univ. Claude Bernard Lyon, F-69626 Villeurbanne, Fr.; Eng.) -Mais 31-144
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