An Efficient Synthesis of Tetraalkyl 2,3,4,5-Thiophenetetracarboxylate Derivatives

Abstract

A facile and direct synthetic entry to tetraalkyl 2,3,4,5-thiophenetetracarboxylate derivatives is described. This involves the reaction of dialkyl acetylenedicarboxylates with elemental sulfur in the presence of triethyl phosphite or an N-heteroaromatic compound such as isoquinoline, 1-methyl-1H-imidazole, or pyridine as catalyst.

Development and Application of Pyridinium 1,4‐Zwitterionic Thiolates: Synthesis of Polysubstituted Thiophenes

“…To our delight, pyridinium 1d bearing a methoxyl group exhibited the best reactivity and furnished the highest yield of 81 % within only 1 h. Then, we adjusted the ratio of reactants, but no better results were obtained. In addition, we also examined a series of common solvents including ethyl acetate, acetone, toluene, and so on (entries [8][9][10][11][12][13][14]. All of them could support the reaction, but only moderate yields were delivered.…”

“…The solid organosulfur compounds are air‐stable, odorless, easy‐ to‐ handle, and readily available. Alizadeh had proposed these thiolates were the key intermediates in the synthesis of tetraalkyl 2,3,4,5‐thiophenetetracarboxylate, but this kind of pyridinium 1,4‐zwitterionic thiolates have not yet been recognized as useful and versatile synthons ever since their emergence, to the best of our knowledge. In this context, intrigued by their unique structures, we envisaged that the reactive intermediates could be used to prepare sulfur‐containing heterocycles via two reaction modes: [5+m, path a], with pyridine as a reactive moiety, and [3+m, path b], with pyridine as a leaving group (Scheme ).…”

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

“…For instance, the reaction of alleneoate 132 and electron-poor alkene 133 in the presence of P(NMe 2 ) 3 catalyst produces 98% yield of 134, whereas in the presence of (4-ClC 6 H 4 ) 3 P as catalyst leads to 92% yield of isomeric cyclohexene 135 (Scheme 59B) [377]. Related to the Rauhut-Currier reaction is the formal (4+1)-cycloaddition of sulfur (S 8 ) with two equivalents of acetylenedicarboxylic esters producing tetraalkyl thiophene-2,3,4,5-tetracarboxylate, a reaction catalyzed by nucleophilic bases such as triethyl phosphite, isoquinoline, pyridine, and N-methylimidazole [378]. An example of catalytic enantioselective intermolecular cross-Rauhut-Currier reaction is given in Scheme 59C [379].…”

“…sulfur (S8) with two equivalents of acetylenedicarboxylic esters producing tetraalkyl thiophene-2,3,4,5-tetracarboxylate, a reaction catalyzed by nucleophilic bases such as triethyl phosphite, isoquinoline, pyridine, and N-methylimidazole [378]. An example of catalytic enantioselective intermolecular cross-Rauhut-Currier reaction is given in Scheme 59C [379].…”

Three-Component Diastereoselective Synthesis of Stable 1,4-Diionic Organosulfurs

“…[9][10][11][12][13] Very recently, Alizadeh et al reported the reaction of acetylenic esters and elemental sulfur in the presence of catalytic amount of N-heterocycle leading to the formation of thiophenetetracarboxylates (Scheme 1). 14 We found that when this reaction is carrying out in the presence of pyridine as the third reagent, not as a catalyst, thiophenetetracarboxylates are not obtained but the stable 1,4-diionic organosulfur compounds are produced (Scheme 1).…”