A safe and fast method for the production of beta-hydroxy-alpha-diazoesters in continuous flow technology is described. The synthesis involves the formation of ethyl diazoacetate in situ and the addition to several aldehydes in a two-step continuous flow microreactor setup. Rhodium acetate catalyzes a subsequent 1,2-hydride shift to give access to beta-keto esters in a three-step sequence.
Silica-Supported Tetramethylguanidine: An Efficient Solid Base for Aldol-Type Coupling of Aldehydes with Ethyl Diazoacetate
Silica-supported tetramethylguanidine catalyst was prepared and effectively used in the aldol-type coupling of aldehydes with ethyl diazoacetate to afford the corresponding α-diazo-β-hydroxy esters in good to excellent yields. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost consistent activity.
A Lewis Acid-Catalyzed Diastereoselective Synthesis of Functionalized 2-Diazo-1,5-dicarbonyl Compounds
作者:Evan M. Howard、Matthias Brewer
DOI:10.1021/acscatal.1c03036
日期:2021.10.1
A diverse array of 2-diazo-1,5-dicarbonyl compounds were formed by the Lewis acid-catalyzed reaction of enoxysilanes with β-hydroxy-α-diazo carbonyls. This reaction proceeds via the Zn(OTf)2-catalyzed dehydroxylation of the β-hydroxy-α-diazo carbonyl to form a vinyl diazonium ion intermediate that is intercepted by the enoxysilane nucleophile to give diazo-containing scaffolds with increased molecular