Transmetalations Mediated By Organocopper Reagents

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This research is being funded by the Organic Synthesis Program. Dr. Lipshutz will continue his very productive studies of organometallic reagents based upon complexes of copper. These have the potential for producing highly selective synthetic tools that can be used in the synthesis of the reactive molecules that are found in nature. This research describes, in part, a number of new synthetic methods which take advantage of the efficiency and mildness of higher order cuprate-based transmetalation processes of organotin compounds. Tolerance to a variety of functional groups within the stannane precursor itself will be studied, looking to form highly functionalized cuprates. Allylic reagents are to be examined with respect to substitutions at both tetrahedral and trigonal centers. Moreover, cyclic allylic stannanes are considered, as is the chemistry of allyl cuprates in the presence of carbon monoxide en route to direct 1,4-acylations of alpha,beta-unsaturated ketones. As part of a program in polyene construction, new lynchpins will be developed which will take advantage of site-selective transmetalations made possible by differences in relative rates between vinylstannanes. Applications to synthetic problems in the leukotriene and pheromone areas will be pointed out. The possibility of using oxidative "decomposition" of higher order cuprates, in a synthetic sense, to effect biaryl couplings will also be studied. The last portion of the research involves spectroscopic investigations of several species. One concerns the nature of the new reagent derived from CuI/LiCl/Bu3SnH, believed to be (X)HCuLi. Another will be an in-depth study of Yamamoto's reagent.