Stille coupling, palladium chemistry

Two of the most frequently used approaches for halothiazole synthesis are direct halogenation of thiazoles and the Sandmeyer reaction of aminothiazoles. The third method, an exchange between a stannylthiazole and a halogen, is not practical in the context of palladium chemistry simply because the stannylthiazole can be used directly in a Stille coupling. 

Palladium-Catalyzed Coupling of Acid Chlorides with Organotin Reagents (E)-Ethyl-4-(4-n1trophenyl)-4-oxo-2-butenoate A, F. Renaldo, J, W. Labadie, and J. K. Stille, Department of Chemistry, Colorado State University, Ft. Collins, CO 80523... 

Stille couplings) show an even wider tolerance towards various functionalities and should therefore allow for the introduction of [ CJmethyl groups at a very late stage of synthetic pathways. Although this has been frequently exploited in carbon-11 chemistry , there are only a few analogous applications in carbon-14 synthesis. The palladium(II)... 

Another palladium-catalysed process that has proven utility for cyclic structures is the Stille coupling between organostannanes and aiyl or vinyl halides/triflates. Specifically for the macrocyclic framework, this chemistry was applied to the preparation of cyclic trienes (102) with defined geometry (Scheme 11.11) that were intermediates for transannular Diels-Alder reactions. The intramolecular Stille reaction also has been efficiently conducted on solid phase to form 104, an advanced intermediate in the synthesis of (S)-zearalenone, from 103 by a cyclization-release strategy. ... 

The palladium component may be added to the reaction mixture as Pd(0)- as well as Pd(II)- compound in the latter case the Pd(II)- first has to be reduced to Pd(0)- by excess stannane. Since the first publication on this coupling method by Stille in 1978, this reaction has gained increased importance in synthetic organic chemistry. This is due to the fact that many different types of substrates can be used in this reaction. The following table lists possible carbon electrophiles and stannanes that can be coupled in any combination. 

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