Terpyridine-supported cobalt alkyl complexes are competent for the diastereoselective hydroboration of substituted indenes to yield 1,3-disubstituted products with near exclusive selectivity for the <i>trans</i> diastereomer. The development of synthetic routes for the selective synthesis of substituted indanes is attractive due to the important pharmacological and bioactive properties exhibited by these carbocyclic structural motifs. In the cobalt-catalyzed hydroboration, alkene insertion and isomerization are proposed to precede carbon-boron bond formation, leading to the observed regioselectivity for boron incorporation at a C(sp<sup>3</sup>)-H bond distal from the starting alkene. Deuterium labeling studies were conducted to explore chain-walking and whether alkene insertion proceeds by 1,2 or 2,1 insertion pathways. Concentration effects and catalyst modification studies have also been conducted to gain insight about competing rates of isomerization versus C-B bond formation. The scope of the protocol as well as its limitations will be presented. A focus on the results of the mechanistic studies as well as a discussion of applications of catalytic products will also be discussed.

Studies into the mechanism of alkene insertion and isomerization in cobalt-catalyzed hydroboration: Applications toward diastereoselective synthesis of 1,3-disubstituted indanes

256th National Meeting (2018)

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