Dehydrogenative Silylation of Alkenes for the Synthesis of Substituted Allylsilanes by Photoredox, Hydrogen‐Atom Transfer, and Cobalt Catalysis

Abstract

As ynergistic catalytic method combining photoredox catalysis,hydrogen-atom transfer,and proton-reduction catalysis for the dehydrogenative silylation of alkenes was developed. With this approach,ahighly concise route to substituted allylsilanes has been achieved under very mild reaction conditions without using oxidants.T his transformation features good to excellent yields,o perational simplicity, and high atom economy.B ased on control experiments, apossible reaction mechanism is proposed. Scheme 1. Strategies for the synthesis of substituted allylsilanes.

Copper‐Photocatalyzed Hydrosilylation of Alkynes and Alkenes under Continuous Flow

“…In 2019, Xu described allylsilanes synthesis through the addition of a silyl radical to an olefin followed by a dehydrogenation event, thanks to the perfect orchestration of three catalytic systems [photoredox, HAT and cobalt catalysis, Eq. (3)] [10] . Wang and Uchiyama described the photocatalytic decarboxylative formation of a silyl radical from silacarboxylic acid followed by the addition to electron‐deficient olefins or styrenes [Eq.…”

Metal-catalyzed silylation of sp3C–H bonds

“…Some silylations leading to sp 3 CH2-SiR3 bond formation will be presented here, although they do not involve a real sp 3 C-H bond catalytic silylation. Three different examples reported by Swabó, 79 Peng-Fei Xu 80 and Zheng Huang 81 will be presented here as they constitute useful approaches to produce reactive sp 3 CH2-SiR3 from allylic compounds and from initial alkane dehydrogenation. The first one involves a classical Pd(II)/Pd(IV) activation of alkene into allyl derivatives, 79 the second one involves a silyl radical formation able to regioselectively add to allylic C=C bond 80 and the third presents the dehydrogenation of alkanes followed by isomerization and hydrosilylation of resulting alkenes.…”

“…Three different examples reported by Swabó, 79 Peng-Fei Xu 80 and Zheng Huang 81 will be presented here as they constitute useful approaches to produce reactive sp 3 CH2-SiR3 from allylic compounds and from initial alkane dehydrogenation. The first one involves a classical Pd(II)/Pd(IV) activation of alkene into allyl derivatives, 79 the second one involves a silyl radical formation able to regioselectively add to allylic C=C bond 80 and the third presents the dehydrogenation of alkanes followed by isomerization and hydrosilylation of resulting alkenes. 81 In 2011 Swabó described the catalytic silylation with Me3Si-SiMe3 of a functional allylic group with sp 3 C-Si bond formation.…”

Cross-Coupling Hydrogen Evolution Reactions

“…2.6 C-Si 键的构筑 烯丙基硅烷类化合物在有机小分子和聚合物合成 中占有重要地位. 许鹏飞课题组 [56] (图 16)结合光催化 剂, 钴肟产氢催化剂和氢原子转移催化剂高效实现了烯 丙基硅烷类化合物的制备. 该脱氢硅烷化反应具有很高 的区域选择性, 优异的官能团耐受性, 广泛的底物适用 性, 是对传统的合成该类化合物需要当量氧化剂的重要 补充.…”