The dual problems of activation of thermodynamically stable precursors and their stereoselective incorporation into other prochiral molecules pose unmet challenges, solutions of which may have broader implications in homogeneous catalysis, and, at a practical level, how we synthesize/manufacture chemical intermediates. In this context, we have discovered new protocols for nearly quantitative and highly selective codimerization of functionalized 1,3-dienes and other alkenes including ethylene and alkyl acrylates. This talk will deal with how the limitations of a highly enantioselctive nickel-catalyzed alkene heterodimerization reaction1 were overcome through the systematic development of new catalysts and optimized reaction conditions. Various strategies for stereochemical control in enantioselective reactions of 1,3-dienes using Co-catalysts will be discussed.2-4 Carefully tailored cobalt catalysts also enable highly enantioselective tandem [2+2| cycloaddition followed by hydrovinylation of enynes for the synthesis of densely functionalized cyclobutanes. The latest generation of catalysts appear to be broadly applicable for highly selective C-C and C-Si bond-forming reactions of various types of alkenes.
1. RajanBabu, T. V.; Cox, A. G; Lim, H. J.; Namura, N.; Sharma, R. K.; Smith C. R.; Zhang, A.‘Hydrovinylation Reactions in Organic Synthesis’, in Comprehensive Organic Synthesis, 2nd edition, Vol. 5, Oxford: Elsevier; 2014. pp. 1582-1620.
2. “Cobalt-Catalyzed Hydrovinylation of 1,3-Dienes”, Timsina, Y. N.; Sharma, R. K.; RajanBabu, T. V. Chem. Sci. 2015, 6, 3994.
3. “Asymmetric Catalysis with Ethylene, Synthesis of Functionalized Enolates”, Biswas, S.; Page J. P.; Dewese, K. R.; RajanBabu, T. V. J. Am. Chem. Soc. 2015, 137, 14268.
4. “Catalytic Enantioselective Heterodimerization of Acrylates and 1,3-Dienes”, Jing, S. M.; Balasanthiran, V.; Pagar, V.; Gallucci, J. C.; RajanBabu, T. V. J. Am. Chem. Soc. 2017, 139, 18034-18043.
(Financial Support: US National Science Foundation, US National Institutes of Health and the Ohio State University)