Carbenoid versus Vinylogous Reactivity in Rhodium(II)-Stabilized Vinylcarbenoids
摘要:
Rhodium(II)-stabilized vinylcarbenoid intermediates display electrophilic character at both the carbenoid site and the vinylogous position. The solvent and catalyst as well as the vinylcarbenoid structure have major effects on the regiochemical outcome of the reaction of vinylcarbenoids with alkenes and dienes. Reaction of vinylcarbenoids with vinyl ethers can lead to the formation of either cyclopropanes or cyclopentenes while reaction of vinylcarbenoids with cyclopentadiene can lead to the formation of either bicyclo[3.2.1]octadiene or bicyclo[2.2.1]heptene derivatives.
Cyclopentene Annulations of Alkene Radical Cations with Vinyl Diazo Species Using Photocatalysis
作者:Francisco J. Sarabia、Qiankun Li、Eric M. Ferreira
DOI:10.1002/anie.201805732
日期:2018.8.20
A direct (3+2) cycloaddition between alkenes and vinyl diazo reagents using either Cr or Ru photocatalysis is described. The intermediacy of a radicalcation species enables a nucleophilic interception by vinyl diazo compounds, a departure from their traditional electrophilic behavior. A variety of cyclopentenes are synthesized using this method, and experimental insights implicate a direct cycloaddition
Visible-light-driven radical 1,3-addition of selenosulfonates to vinyldiazo compounds
作者:Weiyu Li、Lei Zhou
DOI:10.1039/d1gc02036f
日期:——
radical 1,3-selenosulfonylation of vinyldiazo compounds with selenosulfonates, providing various γ-seleno allylic sulfones in good yields. This photochemical reaction was carried out at room temperature in an open flask using ethyl acetate as the solvent without any photocatalysts or additives. The control experiments corroborated that the 1,3-addition proceeded via a radical-chain propagation process. The
[1+1+3] Annulation of Diazoenals and Vinyl Azides: Direct Synthesis of Functionalized 1‐Pyrrolines through Olefination
作者:Vinaykumar Kanchupalli、Sreenivas Katukojvala
DOI:10.1002/anie.201801976
日期:2018.5.4
A dirhodium carboxylate catalyzed [1+1+3] annulation reaction of diazoenals and vinyl azides that gives synthetically important enal‐functionalized 1‐pyrroline derivatives was developed. The reaction involves a novel rhodium‐catalyzed olefination of diazoenals with vinyl azides via electrophilic enal carbenoids, resulting in a new class of enal acrylates. The annulation reaction was used for the direct
Cycloaddition Reactions of Alkene Radical Cations using Iron(III)‐Phenanthroline Complex
作者:Yong Hyun Cho、Jae Hyung Kim、Hyeju An、Kwang‐Hyun Ahn、Eun Joo Kang
DOI:10.1002/adsc.202000191
日期:2020.5.26
oxidation of electron‐rich alkenes using the iron(III)‐phenanthroline complex produced electrophilic alkene radical cations, which promoted efficient radical cation [2+1] cycloaddition reactions with diazo compounds. Subsequent chain propagation afforded tri‐ and tetra‐substituted cyclopropanes. This methodology was also expanded to [3+2] cycloaddition reactions with vinyl diazoesters, validating this sustainable
Gold-Catalyzed Formal [3 + 3] and [4 + 2] Cycloaddition Reactions of Nitrosobenzenes with Alkenylgold Carbenoids
作者:Vinayak Vishnu Pagar、Appaso Mahadev Jadhav、Rai-Shung Liu
DOI:10.1021/ja209980d
日期:2011.12.28
We report two new formal cycloaddition reactions between nitrosobenzenes and alkenylgold carbenoids. We obtained quinoline oxides 3 in satisfactory yields from the gold-catalyzed [3 + 3]-cycloadditions between nitrosobenzenes and alkenyldiazo esters 1. For propargyl esters 5, its resulting gold carbenes react with nitrosobenzene to give alkenylimine 8, followed by a [4 + 2]-cycloaddition with nitrosobenzene