Synthesis of α-Nitro Carbonyls via Nitrations in Flow
作者:Anna Chentsova、Dmitry B. Ushakov、Peter H. Seeberger、Kerry Gilmore
DOI:10.1021/acs.joc.6b01634
日期:2016.10.7
α-nitro esters via the trapping of nitronium ions. The two-stage nitration and subsequent deacetylation of readily available 1,3-dicarbonyl compounds was achieved using a biphasic semicontinuous approach. α-Nitro esters and amides were obtained in good overall yields (53–84%). Some of the α-nitro-1,3-dicarbonyl intermediates exhibit enhanced reactivity and undergo an acid-catalyzed Nef-type reaction to
Cyanoformamides are prevalent as versatile building blocks for accessing synthetically useful intermediates and biologically active compounds. The development of a milder, simpler, and more efficient approach to cyanoformamides is nontrivial. Herein, we demonstrate the effectiveness of 4,S-dioxo-imidazolinium cation activation for transforming 1-aryl-1-carbamoyl oximes to cyanoformamides. By making use of the readily available and highly modifiable dichloroimidazolidinediones (DCIDs), this novel method of activation offers reactivity remarkably greater than that of other reported protocols, exhibits a high functional group compatibility with mild conditions, and could be scaled up easily. More than 30 examples are demonstrated with good to excellent yields in short reaction times. This research not only provides a mild and efficient alternative approach to assembling a portfolio of cyanoformamides but also extends the dichloroimidazolidinedione-mediated chemistry to encompass the C-C bond cleavage reaction.