CATALYTIC METHODS FOR STEREOSELECTIVE SYNTHESIS

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With this award, the Chemical Synthesis (SYN) Program is funding Professor T.V. RajanBabu of the Department of Chemistry at Ohio State University to explore catalytic methods in synthesis. The SYN Program finds particularly notable both the efficient Ni-mediated hydrovinylation transformation, and the impressive regiodivergent Y-salen-mediated aziridine opening chemistry developed in the last cycle. Key features of the research plan in the next cycle include investigation of the mechanism of the efficient stereoselective hydrovinylation reaction and development of an unprecedented asymmetric silyl(boryl)stannylation-diyne cyclization that would give axial chiral cyclic dienes. In most ring-forming reactions, even among highly catalytic and selective ones, the number of functional groups is often depleted in going from an unsaturated starting material to a product. In the aforementioned metal-catalyzed cyclization of diynes, enynes, allenynes and allene-aldehydes mediated by various X-Y reagents (X, Y = [R3Si], [R3Sn], [R2B]), there is a net increase in the number of functional groups in the product of the reaction. Moreover, in the case of the alpha,omega-diyne cyclization, the product (ZZ)-1,2-bis-alkylidene is axially chiral, and transfer of such chirality to centers of chirality around the newly formed ring is projected to add a new dimension to stereocontrol in cyclization reactions. These catalytic processes are part of an underlying green chemistry theme of this and related work in the RajanBabu research group. This theme carries over into the undergraduate organic teaching laboratory in which a project involving an aqueous, asymmetric biocatalytic reduction of unsymmetrical ketones has been introduced. Such a laboratory experience exposes a large undergraduate population to several aspects of modern organic synthesis (e.g., chirality, asymmetric catalysis, green chemistry, structure-activity relationships, separations by chiral stationary phase chromatography).