Palladium‐Catalysed Cross‐Coupling Reactions of Triorganoindium Reagents with Alkenyl Halides

The regio‐ and stereoselectivity of the palladium‐catalysed cross‐coupling reactions of indium organometallics withstereodefined 1‐haloalkenes and 1,1‐dihaloalkenes have been studied. Triorganoindium reagents (R3In; R = alkyl, alkenyl, aryl and alkynyl) can be stereospecifically coupled with stereodefined alkenyl iodides in good yields and short reaction times under palladium catalysis. Additionally, the palladium‐catalysed cross‐coupling reaction of R3In (90 mol‐%) with 1,1‐dibromo‐1‐alkenes gave dicoupling products in high yields. When the reaction was performed with 40 mol‐% of aryl‐, vinyl‐ and alkynylindium derivatives, trans‐selective monosubstitution products were obtained in moderate to good yields. These selective couplings were performed with [Pd2dba3]/P(2‐furyl)3 (1:1, 2 mol‐%) at 0 °C or, for 1,1‐dibromo‐1‐alkenes with an aromatic group in the β‐position, [Pd(DPEPhos)Cl2] (2 mol‐%) at room temperature as the catalytic system. The resulting (Z)‐monobromoalkenes can be further functionalized by cross‐coupling reaction with various R3In (R = alkyl, aryl and alkynyl) in the presence of [Pd(tBu3P)2] as catalyst, at room temperature, to provide trisubstituted olefins in good yields.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)