Rh(III)-Catalyzed Cyclopropanation Initiated by C–H Activation: Ligand Development Enables a Diastereoselective [2 + 1] Annulation of N-Enoxyphthalimides and Alkenes
作者:Tiffany Piou、Tomislav Rovis
DOI:10.1021/ja506579t
日期:2014.8.13
N-Enoxyphthalimides undergo a Rh(III)-catalyzedC–Hactivationinitiatedcyclopropanation of electron deficient alkenes. The reaction is proposed to proceed via a directed activation of the olefinic C–H bond followed by two migratory insertions, first across the electron-deficient alkene and then by cyclization back onto the enol moiety. A newly designed isopropylcyclopentadienyl ligand drastically
The direct preparation of functionalised cyclopropanes from allylic alcohols or α-hydroxyketones using tandem oxidation processes
作者:Graeme D. McAllister、Magalie F. Oswald、Richard J. Paxton、Steven A. Raw、Richard J.K. Taylor
DOI:10.1016/j.tet.2005.12.078
日期:2006.7
carried out in the presence of a stabilised sulfurane, and the intermediate α,β-unsaturated carbonyl compound undergoes in situ cyclopropanation. By using a combination of stabilisedphosphorane and sulfurane, the direct conversion of allylic alcohols or α-hydroxyketones into functionalised cyclopropanes is achieved, with in situ cyclopropanation being followed by Wittig olefination, or vice versa. The
Tandem Oxidation Processes for the Preparation of Functionalized Cyclopropanes
作者:Magalie F. Oswald、Steven A. Raw、Richard J. K. Taylor
DOI:10.1021/ol0483394
日期:2004.10.1
[reaction: see text] A novelmanganese dioxide-mediated tandem oxidation process (TOP) has been developed which allows the direct conversion of allylicalcohols into cyclopropanes, the intermediate aldehydes being trapped in situ with a stabilized sulfur-ylide. This methodology has been applied successfully to a variety of allylicalcohols and to a formal synthesis of the simple, naturally occurring
Facile construction of three-membered rings via benzyne-promoted Darzens-type reaction of tertiary amines
作者:Ya-Nan Xu、Shi-Kai Tian
DOI:10.1016/j.tet.2018.11.065
日期:2019.3
A range of tertiary amines having electron-withdrawing groups were activated in situ by benzyne, generated from 2-(trimethylsilyl)phenyl triflate and a fluoride source, and participated in the Darzens-type reaction with carbonyl compounds, imines, and vinyl ketones to afford structurally diverse epoxides, aziridines, and cyclopropanes, respectively, in moderate to excellent yields with high trans-selectivity
Enantioselective Photocatalytic [3 + 2] Cycloadditions of Aryl Cyclopropyl Ketones
作者:Adrian G. Amador、Evan M. Sherbrook、Tehshik P. Yoon
DOI:10.1021/jacs.6b01728
日期:2016.4.13
Control of stereochemistry in photocycloaddition reactions remains a substantial challenge; almost all successful catalytic examples to date have involved [2 + 2] photocycloadditions of enones. We report a method for the asymmetric [3 + 2] photocycloaddition of aryl cyclopropyl ketones that enables the enantiocontrolled construction of densely substituted cyclopentane structures not synthetically accessible