Direct Enamido C(sp<sup>2</sup>)−H Diphosphorylation Enabled by a PCET‐Triggered Double Radical Relay: Access to<i>gem</i>‐Bisphosphonates
作者:Hao‐Qiang Cao、Hao‐Nan Liu、Zhe‐Yuan Liu、Bao‐Kun Qiao、Fa‐Guang Zhang、Jun‐An Ma
DOI:10.1002/chem.202000517
日期:2020.4.24
electron-transfer (PCET)-triggered enamidoC(sp2 )-Hdiphosphorylation. This reaction represents a rare example of realizing the challenging double C-P bond formation at a single carbon atom, thus providing facile access to a broad variety of structurally diverse bisphosphonates from simple enamides under silver-mediated conditions. Initial mechanistic studies demonstrated that the diphosphorylation involves
reaction proceeds in the presence of CO, thus providing a synthesis for 1,3‐oxazin‐6‐ones (see scheme; DABCO=1,4‐diazabicyclo[2.2.2]octane, DMF=N,N‐dimethylformamide). The reaction tolerates a variety of functional groups on both the aryl ring and the amide of the substrate. Initial mechanistic studies suggest the activation of the alkenylCH bond to be a key step.
is a fundamental concept in organic chemistry, which provides an alternative strategy for the synthesis of target compounds which were not easily accessible by conventional methods. Herein, a mild and efficient PhI(OAc)2-promoted umpolung acetoxylation reactions of enamides was developed for the synthesis of α-acetoxy ketones. The reaction tolerates a wide range of functional groups and affords α-acetoxy
A novel palladium-catalyzedoxidative cyclopropanation of enamides and norbornenes has been developed. The reaction proceeded through palladium-catalyzed vinyl C–H bond activation of enamides followed by two migratory insertions, β-(N)H elimination and hydrolyzation cascade steps. The reaction tolerates a range of functional groups and provides an effective method for the synthesis of cyclopropane-fused
CuI-catalyzed reductive acylation of ketoximes for preparation of enamides was reported. A broad scope of enamides was obtained in high yields with NaHSO3 used as the terminal reductant.