为了满足对快速、流线型和潜在自动化分子合成的需求,非常需要模块化耦合方法。虽然芳族分子的多样化,即C sp2空间,已经取得了很大进展,但C sp3空间中的模块合成相对而言发展得少得多。本报告探讨了替代功能手柄的潜力,即烷基锗烷,在这种情况下,它结合了稳定性和可合成性的特征与选择性反应性。我们展示了烷基锗烷 (R-GeEt 3 ) 在光氧化还原条件下(Giese 加成)的化学选择性功能化以及在模块化构建块中的实现,这允许 C 的选择性多样化sp3 -halogen vs C sp3 -Bpin vs C sp3 -GeEt 3个位点。
Microtubing-Reactor-Assisted Aliphatic C−H Functionalization with HCl as a Hydrogen-Atom-Transfer Catalyst Precursor in Conjunction with an Organic Photoredox Catalyst
作者:Hong-Ping Deng、Quan Zhou、Jie Wu
DOI:10.1002/anie.201804844
日期:2018.9.24
Chlorine radical, which is classically generated by the homolysis of Cl2 under UV irradiation, can abstract a hydrogenatomfrom an unactivated C(sp3)−H bond. We herein demonstrate the use of HCl as an effective hydrogen‐atom‐transfer catalyst precursor activated by an organic acridinium photoredox catalyst under visible‐light irradiation for C−H alkylation and allylation. The key to success relied
effective direct hydrogen‐atom transfer catalyst for C−H activation. Using the alkylation of C−Hbonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C−Hbonds in a green
the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and alkylation of hydrocarbons, this reaction
achieved in a highly selective fashion. This study represents the first example of selective activation of unactivated alkanes by bromine radicals in a catalytic and metal-free manner. Good reactivity was achieved by using a sealed microtubing reactor or by adding a proper amount of water. This highly selective C(sp3)–H functionalization protocol offers a new paradigm for the direct synthesis of valuable compounds
Uranyl nitrate hexahydrate performs as an efficient photocatalyst in the direct C–H to C–C bond conversion under blue light irradiation via hydrogen atom transfer (HAT). This uranyl salt enables the remarkable smooth functionalization of unactivated (cyclo)alkanes, ethers, acetals, and amides via radical addition onto electrophilic olefins. Dedicated electrochemical measurements on compounds and intermediates