N-heterocyclic carbene catalysis promoted the unprecedented decarboxylative coupling of aryl aldehydes and tertiary or secondary alkyl carboxylic acid-derived redox-active esters to produce aryl alkyl ketones. The mild and transition-metal-free reaction conditions are attractive features of this method. The power of this protocol was demonstrated by the functionalization of pharmaceutical drugs and natural
The N-heterocycliccarbene-catalyzed radical relay enables the vicinal alkylacylation of styrenes, acrylates and acrylo-nitrile using aldehydes and tertiary alkyl carboxylic acid-derived redox-active esters. This protocol introduces tertiary alkyl groups and acyl groups to C-C double bonds with complete regioselectivity to produce functionalized ketone derivatives. The radical relay mechanism involves
N-杂环卡宾催化的自由基中继能够使用醛和叔烷基羧酸衍生的氧化还原活性酯对苯乙烯、丙烯酸酯和丙烯腈进行邻位烷基酰化。该协议将叔烷基和酰基引入 CC 双键,具有完全的区域选择性,以产生功能化的酮衍生物。自由基中继机制涉及从 Breslow 中间体的烯醇化物形式的单电子转移和所得烷基自由基与烯烃的自由基加成,然后是自由基 - 自由基偶联。
C–O σ-bonds in multifaceted benzoin derivatives can be effectively cleaved as acetates using catalytic amounts of [Ru(bpy)3]Cl2 as photoredox catalyst in combination with Hantzsch ester and triethylamine as a sacrificial electron donor. This mild and operationally simple method is applicable to a great variety of substrates. Homo- and cross-benzoins, which are easily accessed by NHC (N-heterocyclic
Metal-Free Reductive Cleavage of C−O σ-bonds in Acyloin Derivatives by an Organic Neutral Super-Electron-Donor
作者:Sylvain P. Y. Cutulic、Neil J. Findlay、Sheng-Ze Zhou、Ewan J. T. Chrystal、John A. Murphy
DOI:10.1021/jo901815t
日期:2009.11.20
Neutral organic electron-donor 7, formally a pyridinylidene carbene dimer, effects reductivecleavage of C−O σ-bonds in acyloin derivatives Ar(CO)CRR′OX (X = OAc, OPiv, OBz, OMs) and this represents the first cleavage of C−O σ-bonds by a neutral organic electron-donor. The methodology is applicable to a large array of substrates and the reduced counterparts were isolated in good to excellent yields
Hydrogen peroxide and anhydride mediated transformation of enamides to afford substituted α-acyloxy ketones is described. This transition-metal-free cascade reaction has a broad substrate scope and high efficiency. The acyl intramolecular migration procedure successfully achieved this acyloxylation process under mild conditions and increased the atom efficiency.