a new desulfurative method for generating primary, secondary, and tertiary alkyl radicals through visible‐light photoredoxcatalysis. A process that involves the generation of N‐centered radicalsfrom sulfinamide intermediates, followed by subsequent fragmentation, is critical to forming the corresponding alkyl radical species. This strategy has been successfully applied to conjugate addition reactions
A simple generation method of carbon radicals via 1e-oxidation of organotrifluoroborates and carboxylic acids by the action of an organophotoredox catalyst, 9-mesityl-10-methylacridinium perchlorate ([Acr+–Mes]ClO4), has been developed. This organophotocatalytic protocol is amenable to radical C–C bond formation with electron-deficient olefins.
photocatalytic Giese‐type reaction with alkylsilicates bearing C,O‐bidentate ligands as stable alkyl radical precursors has been reported. The alkylsilicates were prepared in one step from organometallic reagents. Not only primary, secondary, and tertiary alkyl radicals, but also elusive methyl radicals, could be generated by using the present reaction system. The generated radicals were trapped by electron‐deficient
A series of hydrogen-atomtransfer (HAT) catalysts based on the readily available and tunable 1,4-diazabicyclo[2.2.2]octane (DABCO) structure was designed, and their photoinduced HAT catalysis ability was demonstrated. The combination of our HAT catalyst with an acridinium-based organophotoredox catalyst enables efficient and site-selective C–H alkylation of substrates ranging from unactivated hydrocarbons
设计了一系列基于容易获得且可调的 1,4-二氮杂双环[2.2.2]辛烷 (DABCO) 结构的氢原子转移 (HAT) 催化剂,并证明了它们的光诱导 HAT 催化能力。我们的 HAT 催化剂与基于吖啶的有机光氧化还原催化剂相结合,可以对从未活化的碳氢化合物到复杂分子的底物进行高效和位点选择性的 C-H 烷基化。值得注意的是,具有与氮原子相邻的附加取代基的 HAT 催化剂进一步提高了位点选择性。机理研究表明,催化剂的N取代基起着至关重要的作用,有助于生成双阳离子胺自由基作为 HAT 过程的活性物质。
Hydroalkylation of Alkenes Using Alkyl Iodides and Hantzsch Ester under Palladium/Light System
作者:Shuhei Sumino、Ilhyong Ryu
DOI:10.1021/acs.orglett.5b03238
日期:2016.1.4
The hydroalkylation of alkenes using alkyl iodides with Hantzsch ester as a hydrogen source occurred smoothly under a Pd/light system, in a novel, tin-free Giese reaction. A chemoselective reaction at C(sp(3))-I in the presence of a C(sp(2))-X (X = Br or I) bond was attained, which allowed for the stepwise functionalization of two types of C-X bonds in a one-pot procedure.