TFAA/H₃PO₄‐Mediated C‐2 Acylation of Thiophene: A Direct Synthesis of Known and Novel Thiophene Derivatives of Pharmacological Interest

A One-Pot Assembly of Fully Substituted Alkyl 5-Aminothiophene-2-carboxylates from Allenes, Isothiocyanates, and Alkyl 2-Bromoacetates

“…Thiophenes are privileged five-membered sulfa-heterocycles, which have widespread use in pharmacology, agrochemistry, materials science, combinatorial and medicinal chemistry, and many other fields . Among them, aminothiophenes, thiophenecarboxylates, and thiophenes bearing amino and carboxylate functions are one of the most popular structural motifs, especially in recent times. They have a broad spectrum of biological activity, are part of many pharmaceuticals including drugs for treatment of socially significant diseases (HIV, tuberculosis, cancer, flu, etc.…”

2H-Pyran-2-one-Functionalized Diketopyrrolopyrrole Dye: Design, Synthesis, and Explosives Sensor

“…For this purpose, at first, the synthesis of thionyl-DPP derivative 3 was achieved in two steps . A modified Friedel–Crafts electrophilic acylation reaction of 3 in the presence of H 3 PO 4 /acetic anhydride, which leads to a mixture of mono -( 4a ) and di -acetyl-( 4b ) DPP derivatives . The isolated yields of 4a and 4b were 22 and 28%, respectively.…”

New method for the acylation of benzofurans toward the synthesis of 6H-indeno[2,1-b]benzofuran-6-ones and 2,2-bibenzofurans

“…10,11 2-Acylbenzofurans can also be obtained by Lewis acid catalyzed acylation of benzofurans using acid anhydrides or acyl chlorides as acylating agents (Scheme 1b). [12][13][14][15] The trifluoroacetic anhydride (TFAA)-mediated acylation 16 using carboxylic acids as the acylating agent have been applied to arenes 17 and heteroarenes including thiophenes, 18 benzothiophenes, 19 pyrroles, 20 and carbazoles. 21 However, to the best of our knowledge, this protocol has never been used with benzofurans, although a single literature precedent with furans as substrates has been reported.…”