Popularized by the Suzuki reaction, organoboronate esters and boronic acids are now regarded as key building blocks in numerous synthetic pathways to complex organic materials with interests ranging from material to life science. Consequently, numerous methodologies have been reported to access these valuable substrates. In that respect, the catalytic dehydrogenative borylation of carbon-hydrogen bonds with dialkoxyboranes (RO)2BH is regarded as being both step and atom economical. Following a ground breaking report by Hartwig and others, the dehydrogenative borylations are now well documented for C(sp3)-H and C(sp2)-H bonds. With respect to terminal alkynes, however, reports are still scarce as the process is in competition with the hydroboration of the triple bond yielding preferentially the anti-Markovnikov alkenylborane adducts. Following the report by Ozerov and coworkers,[1] we developed a CAACCuX catalytic system capable of achieving selectively the dehydroboration reaction of alkynes without compromising efficiency and scalability. Besides the obvious advantages (cheap metal, commercially available ligands, stoichiometric loadings of substrates), this catalytic system can be tuned to obtain selectively the α-hydroboration product. The scope of our methodology will be briefly presented, together with a discussion of the mechanistic investigations we have performed. 1. Lee, C.-I.; Zhou, J.; Ozerov, O. V. J. Am. Chem. Soc. 2013, 135, 3560-3566.

Cyclic (alkyl) (amino) carbene copper (I) catalyzed dehydrogenative borylation and α-hydroboration of terminal alkynes

251st National Meeting (2016)

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