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Synthesis 2006(1): 111-114  
DOI: 10.1055/s-2005-921749
PAPER
© Georg Thieme Verlag Stuttgart · New York

Cross-Coupling of Aryl Halides and Triflates with Group 13-Metal Alkylating Reagents by Palladium-Molybdenum and Palladium-Tungsten Mixed-Metal Catalysts

Margarita Shenglofa, Gary A. Molanderb, Jochanan Blum*a
a Department of Organic Chemistry, Hebrew University, Jerusalem 91904, Israel
Fax: +972(2)6513832; e-Mail: jblum@chem.ch.huji.ac.il;
b Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
Fax: +1(215)5737165; e-Mail: gmolandr@sas.upenn.edu;
Further Information

Publication History

Received 27 June 2005
Publication Date:
16 December 2005 (online)

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Abstract

The palladium-containing clusters {MoPdcp[µ-(CO)2][µ3-(CO)](PPh3)}2 (1) and {PdWcp[µ-(CO)2][µ3-(CO)](PPh3)}2 (2) catalyze the cross-methylation and ethylation of aryl halides and triflates with the respective intramolecularly stabilized dialkylaluminum, gallium and indium reagents 3-7 at temperatures between 78 °C and 120 °C. Unlike the conventional mononuclear palladium catalysts, complexes 1 and 2 promote the coupling of aryl chlorides and show no signs of homocoupling or hydrogenolysis even when the alkylating moieties contain β-hydrogen atoms. The catalytic activity and selectivity of the mixed-metal clusters is attributed to synergism between the different metal nuclei of the catalysts.

Key words

cross-coupling - mixed-metal catalysts - palladium - ­molybdenum - tungsten