Silver-mediated annulation between 5-H-1,2,3-thiadiazoles and 1,3-dicarbonyl compounds to construct polysubstituted furans

Abstract

An efficient synthesis of polysubstituted furans by Ag(I)-mediated annulation between 5-H-1,2,3-thiadiazoles and 1,3-dicarbonyl compounds was reported. The methodology was characterized by availablility of starting materials, good functional group tolerance, and...

The effect of the C5-substituent on regioselectivity in the Rh(i)-catalyzed intermolecular transannulation of 1,2,3-thiadiazoles with phenylacetylene

“…Transition metal-catalyzed denitrogenative transformations of 1,2,3-thiadiazoles have been demonstrated to be a facile and highly efficient approach to access structurally diverse heterocycles, [1][2][3] including thiophenes, [4][5][6][7][8] thiazoles, 9 isothiazoles, [10][11][12] 4H-thiopyran-4-ones, 13 thiochromenones, 14 1,3-thiaphospholes 15 and furans. 7,16 The mechanism of denitrogenative 1,2,3-thiadiazole transannulation reactions was investigated by Bao in 2021 using density functional theory (DFT) calculations, 17 with the structure of the key cyclometalated Rh(III) intermediate recently confirmed by our group using crystallographic data. 7 The general mechanism involves initial 1,2,3-thiadiazole ring-opening and subsequent denitrogenation, leading to formation of the cyclometalated organorhodium intermediate (Scheme 1a).…”

Alkyne/thio umpolung tactic replacement: synthesis of alkynyl sulfides via capturing the in situ formed alkynylthiolate anion

“…13 However, the harsh conditions, that is in the presence of nBuLi at −60 °C, significantly inhibit its synthetic applications. Owing to our continuous interest in the transformations of 1,2,3-thiadiazoles, 12,14 considering the rare report and the lack of exploration of synthetic applications of alkynylthio nucleophile intermediates, we wondered whether the in situ formed alkynylthiolate anion intermediate could be used for transition-metal catalyzed cross-coupling reactions.…”

Regioselectivity for the Rh(I)‐catalyzed Annulation of 1,2,3‐Thiadiazoles with Alkynes: Experimental and Computational Analysis Reveal the Surprising Role of the Alkyne Substituent

“…Among the different types of building blocks examined for denitrogenative annulation, diazocarbonyl compounds and 1,2,3‐triazoles are relatively well explored, allowing a range of oxygen‐ and nitrogen‐containing heterocycles to be accessed [7] . In 2016, the seminal work of Gevorgyan demonstrated that rhodium‐catalyzed denitrogenation of 1,2,3‐thiadiazoles is possible, allowing arrange of valuable sulfur‐containing heterocycles to be synthesised, [8] including thiophenes, [8a,9] thiazoles, [10] isothiazoles, [11] 4 H ‐thiopyran‐4‐ones, [12] thiochromenones, [13] 1,3‐thiaphospholes [14] and furans [9c,15] . The increasing application of 1,2,3‐thiadiazoles in synthesis has led to a range of synthetic approaches to 1,2,3‐thiadiazoles being developed [8d,11c,16] …”