DEVELOPMENT OF STILLE CROSS COUPLINGS THAT ARE CATALYTIC IN TIN

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We recognize that refinements in biological screening protocols will allow scientists to discover pharmacologically significant natural products that are available in only minute quantities. In such cases, the power of organic synthesis will undoubtedly be called upon to provide sufficient material for full biological evaluation. Given natures propensity for structurally complicated molecules, this is sure to be quite a challenge for synthetic chemists. To address this challenge we look to invent unique catalytic reactions and strategies that are of high efficiency and general utility. The use of stoichiometric amounts of organotin compounds in palladium-mediated divinyl cross-couplings, aminations, and related reactions is a primary disadvantage of the Stille coupling protocol. The invention and development of new methods allowing for the catalytic employment of organostannanes in such reactions would significantly reduce the amount of tin waste and thereby be of great value with respect to both environmental and practical concerns. The specific aim of this research program is the development of reaction procedures which will allow for the in situ generation of organotins and their subsequent coupling or amination under conditions that are catalytic in tin as well as palladium. In support of this research it is essential that advanced mass spectral facilities be available to provide high resolution spectra of our synthetic compounds.