Heck reactions of aryl halides with alk-1-en-3-ol derivatives catalysed by a tetraphosphine-palladium complex

cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane-[PdCl(C3H5)](2) efficiently catalyses the Heck reaction of alk-1-en-3-ol with a variety of aryl halides. In the presence of hex-1-en-3-ol or oct-1-en-3-ol, the beta-arylated carbonyl compounds were selectively obtained. Turnover numbers up to 84 000 can be obtained for this reaction. Linalool and 2-methylbut-3-en-2-ol led regio- and stereoselectively to the corresponding (E)-1-arylalk-1-en-3-ol derivatives. A minor electronic effect of the substituents of the aryl bromide was observed. Quite similar reaction rates were generally observed in the presence of activated aryl bromides such as bromoacetophenone and deactivated aryl bromides such as bromoanisole, indicating that, with these alkenols and this catalyst, the oxidative addition of aryl bromides to palladium is not the rate-limiting step. It should be noted that this reaction also proceeds with sterically very congested aryl bromides such as 9-bromoanthracene or 2,4,6-triisopropylbromobenzene or with a vinyl bromide. On the other hand, low yields were obtained with aryl chlorides. Copyright (c) 2006 John Wiley & Sons, Ltd.