Selectfluor-Mediated Simultaneous Cleavage of C–O and C–C Bonds in α,β-Epoxy Ketones Under Transition-Metal-Free Conditions: A Route to 1,2-Diketones
作者:Heng Wang、Shaobo Ren、Jian Zhang、Wei Zhang、Yunkui Liu
DOI:10.1021/acs.joc.5b00857
日期:2015.7.2
Selectfluor-mediated simultaneous cleavage of C–O and C–C bonds in α,β-epoxyketones has been successfully achieved under transition-metal-free conditions. The reaction gives 1,2-diketone compounds in moderate to good yields involving a ring-opening/benzoyl rearrangement/C–C bond cleavage sequence under oxidative conditions.
An efficient and practical method for the synthesis of unsymmetricbenzils from readily available β-ketoaldehydes has been developed. Various unsymmetric 1,2-diaryldiketones bearing functional groups have been obtained in good to excellent yields under mild reaction conditions. A plausible mechanism was proposed, and α,α-dichloroketone was considered as the key intermediate. The generation of α,α-dichloroketones
Waste minimization is a very important aspect of an environmentally benign protocol. A one-pot consec-process has been developed for chalcone epoxide synthesis that allows compounds to be prepared having to isolate and purify the intermediates. The strategy utilizes consecutive Claisen Schmidt and epoxidation reactions to prepare chalcone epoxides from substituted benzaldehydes acetophenones in good yields. (C) 2014 Elsevier Ltd. All rights reserved.
Visible-Light-Promoted Photoredox Syntheses of α,β-Epoxy Ketones from Styrenes and Benzaldehydes under Alkaline Conditions
作者:Jing Li、David Zhigang Wang
DOI:10.1021/acs.orglett.5b02629
日期:2015.11.6
A range of styrenes and benzaldehydes were smoothly combined to form alpha,beta-epoxy ketones under the synergistic actions of photocatalyst Ru(bpy)(3)Cl-2, tert-butyl hydroperoxide (t-BuOOH), cesium carbonate (Cs2CO3), and visible light irradiation. The process likely proceeds through visible-light-enabled photocatalytic generations of acyl radicals as key intermediates.
Highly Diastereo- and Enantioselective Organocatalytic Domino Michael/Aldol Reaction of Acyclic 3-Halogeno-1,2-Diones to α,β-Unsaturated Aldehydes
作者:Alice Lefranc、Laure Guénée、Alexandre Alexakis
DOI:10.1021/ol400697n
日期:2013.5.3
The first organocatalyticdiastereo- and enantioselective domino Michael/aldol reaction of 3-halogeno-1,2-diones to α,β-unsaturated aldehydes has been achieved. This transformation tolerates a large variety of electronically different substituents on both reactive partners and allows the synthesis of challenging cyclopentanone derivatives with four contiguous stereogenic centers in excellent diastereoselectivities