Claisen type Condensation of Methyl Ketones with Carbimidothioates: A New Gateway for the Synthesis of β‐Enaminones

Abstract

Carbimidothioates are synthesized by the reaction of Grignard reagents or heteroaryl lithium compounds with arylisothiocyanates followed by treatment with methyl iodide. Further, application of these intermediates in the synthesis of β‐enaminones by their condensation with methyl ketones in the presence of sodium hydride in DMF is reported. This method offers a new gateway for the synthesis of β‐enaminones, which are important building blocks in synthetic organic chemistry.

An Efficient Route for the Synthesis of 1,5‐Disubstituted Tetrazoles and their Anti‐Microbial Activity Against Salmonella Paratyphi

“…The required intermediates carbimidothioates were synthesized according to our earlier reported protocol [16k] . reaction of aryl bromides 1 with magnesium in the presence of catalytic amount of iodine formed the Grignard reagents 2 .…”

“…In spite of these available methods in the literature, still new synthetic methods are in demand because aforementioned methods exhibits limitations such as use of toxic reagents and unstable substrates, low yields, formation of regioisomers etc. In continuation of our efforts towards the development of new organosulfur intermediates and exploration of their synthetic applications, [16] and we have recently reported the synthesis of β ‐enaminones by the Claisen‐type condensation of methyl ketones with carbimidothioates (Scheme 1a) [16k] . In extension of this work, with the aim to explore the synthetic applications of carbimidothioates, here, we reported the thermal cyclization of sodium azide with carbimidothioates to get tetrazoles (Scheme 1b).…”

Cyclocondensation of o‐Phenylenediamines with 2‐Oxo‐ethanimidothioates: A Novel Synthesis of 2‐Amino‐3‐(het)aryl‐quinoxalines

“…[27] Recently, we have reported the synthesis of β-enaminones by condensing carbimidothiates with methyl ketones. [28] In continuation of our work on development of new synthetic methods for the synthesis of heterocyclic compounds, [29] we herein report the condensation of oxoethanimidothioates with o-phenylenediamine in the presence of p-TSA, which allowed the formation of 2-amino-3-(het)arylquinoxalines (Scheme 1b). To the best of our knowledge, this reaction has not been reported in the literature.…”

“…We are successfully exploring the synthetic efficacy of α ‐oxodithioester by reporting 2‐acylbenzoxazole/2,3‐disubstituted quinoxaline by condensing with o ‐phenylenediamine/ o ‐aminophenol and 4,5‐di substituted thiazoles by cyclising with active methylene isocyanide (Scheme 1a) [27] . Recently, we have reported the synthesis of β ‐enaminones by condensing carbimidothiates with methyl ketones [28] . In continuation of our work on development of new synthetic methods for the synthesis of heterocyclic compounds, [29] we herein report the condensation of oxoethanimidothioates with o ‐phenylenediamine in the presence of p ‐TSA, which allowed the formation of 2‐amino‐3‐(het)arylquinoxalines (Scheme 1b).…”

A panoramic view on synthetic applications of α-oxothioamides: a highly regioselective synthesis of 2-acyl-4-(het)arylthiazoles and thioethers

“…In continuation of our efforts in organic synthesis [38][39][40][41][42][43][44] we have recently reported the synthesis of quinoxalines, 45,46 thiazoles 47 and benzoxazoles 45 from a-ketodithioesters. In this direction, we have recently reported the synthesis of a-ketothioamides and explored their applications for the synthesis of 3,5-bis(acyl)-1,2,4-thiadiazoles.…”