Copper-catalyzed regio- and stereo-selective hydrosilylation of terminal allenes to access (E)-allylsilanes

Abstract

Regioselectivity and stereoselectivity control in hydrosilylation of terminal allenes is challeging. Although the selective synthesis of vinylsilanes, branched allylsilanes or linear (Z)-allylsilanes have been achieved, transition-metal catalyzed hydrosilylation of terminal allenes to access (E)-allylsilane is difficult. Herein, we report a copper-catalyzed selective hydrosilylation reaction of terminal allenes to access (E)-allylsilanes under mild reaction conditions. The reaction shows broad substrate scope, representing an efficient method to prepare trisubstituted (E)-allylsilanes through hydrosilylation reaction of allenes and can also be applied in the synthesis of disubstituted (E)-allylsilanes. The mechanism study reveals that the E-selectivity is kinetically controlled by the catalyst but not by the thermodynamically isomerization of the (Z)-isomer.

Enantioselective Nickel‐Catalyzed Hydrosilylation of 1,1‐Disubstituted Allenes

“…Inspired by recent experimental and computational studies on the M II ‐catalyzed (M=Cu, Co) hydrosilylation of allenes, [7l, 9] and alkenes, [4h, 19] in which the M I ‐hydride was considered as the active species, we investigated the reaction pathway that initiated with the Ni I ‐hydride complex. Although we didn't observe the direct experimental evidences for the Ni I −H species, the formation of the Ni I ‐hydride complex is computed to be thermodynamically feasible (For details, see Supporting Information).…”

Metal-free photocatalyzed allylic silylation of allyl acetates and chlorides

“…For example, Watson's group reported a Pd-catalyzed silyl Heck reaction to afford allylsilanes employing terminal alkenes and TMSI. 8 Regioselective hydrosilylation of 1,3-dienes 9 and allenes 10 were well developed and dehydrogenative silylation reactions of alkenes also emerged as an atom-economic tool. 11 Recently, Zhao and co-workers reported Ni-catalyzed chemodivergent reactions of silacyclobutanes with alkynes, forming silicon-stereogenic allyl vinylsilanes.…”

Regio- and enantioselective CuH-catalyzed 1,2- and 1,4-hydrosilylation of 1,3-enynes

“…To the best of our knowledge, selective 1,2-hydrosilylation reaction of 1,3-enynes has not been described. Owing to the high reactivity of allene moiety, an additional challenge in 1,4-hydrosilylation of 1,3-enynes comes from the undesired further hydrosilylation of allenylsilane product 63 – 65 . In addition, only a couple of examples realized selective 1,4-hydrosilylation of 1,3-enynes, and most of them exhibited narrow substrate scope 58 – 62 .…”