The selective addition of organomagnesium reagents to 2,4,6‐trichlorophenyl isocyanide leading to magnesiated aldimines is reported. These aldimines react with Weinreb amides, ketones, or carbonates to provide the corresponding carbonyl derivatives after acidic cleavage. This allows for an efficient synthesis of 1,2‐dicarbonyl compounds and α‐hydroxy ketones.
A Desulfonylative Approach in Oxidative Gold Catalysis: Regiospecific Access to Donor‐Substituted Acyl Gold Carbenes
作者:Hongyi Chen、Liming Zhang
DOI:10.1002/anie.201504511
日期:2015.9.28
Donor‐substitutedacylgoldcarbenes are challenging to access selectively by gold‐promoted intermolecular oxidation of internal alkynes as the opposite regioisomers frequently predominate. By using alkynyl sulfones or sulfonates as substrates, the oxidativegoldcatalysis in the presence of substituted pyridine N‐oxides offers regiospecificaccess to acyl/aryl, acyl/alkenyl, and acyl/alkoxy gold carbenes
Synthesis of Symmetrically and Unsymmetrically Substituted .alpha.-Diones from Organometallic Reagents and 1,4-Dialkylpiperazine-2,3-diones
作者:Ulrich T. Mueller-Westerhoff、Ming Zhou
DOI:10.1021/jo00096a049
日期:1994.8
The reaction of an equimolar mixture of N,N'-dialkylethylenediamines and diethyl oxalate in diethyl ether or 2-propanol leads to 1,4-dialkylpiperazine-2,3-diones. As cyclic and nearly planar tetraalkyl oxamides, these compounds are able to react with 2 equiv of organolithium or Grignard compounds to form, after hydrolysis, symmetrically substituted alpha-diones in excellent yields. The sequential addition of 1 equiv each of two different organolithium compounds affords unsymmetrically substitute alpha-diones when the more soluble longer chain dialkyl derivatives of piperazine-2,3-dione are employed. The dialkylethylenediamines can conveniently be recovered and recycled to the 1,4-dialkylpiperazine-2,3-diones in good yields.