Facile synthesis of 3-substituted thieno[3,2-b]furan derivatives

Dimethyl Acetylenedicarboxylate: A Versatile Tool in Organic Synthesis

“…The Michael reaction between methyl thioglycolate and DMAD, followed by in situ intramolecular cyclization, afforded the 3-hydroxythiophene 60 in 85% yield (Scheme 17). 21 The reaction of DMAD with arylidenemalononitriles 62, in the presence of potassium isothiocyanate in acetonitrile, led to a mixture of cyanothiophene 63 and dicyanocyclopenta-1,3-diene derivatives 64. It was proposed that this multicomponent reaction could have been started with the addition of isothiocyanate ion to DMAD (Michael reaction) followed by addition of 62 (Scheme 18).…”

Flash vacuum pyrolysis of oxo-stabilised phosphonium ylides containing methoxythiophene and methylthiophene groups

“…In view of the success in replacing the starting benzene ring of 1 with pyridine in 3, we were interested to see whether the thermodynamically stable thiophene ring could also be used and thus we examined a range of methoxythienyl ylides as a potential route to fused ring thiophene products. The expected thienofurans are relatively inaccessible heterocycles [10] and typical routes to thieno [3,2-b]furans [11][12][13][14] and thieno [3,4-b]furans [14][15][16] often involve several steps and require certain groups to be present. We have also recently encountered unexpected rearrangements of thiophenes under FVP conditions [17], and we include here also an account of further unexpected thermal processes involving oxo ylides containing a methylthienyl group.…”

Regioselective Thorpe–Ziegler Cyclization of 3-O-Alkylated Thiophenes; Access to Aminothieno[3,2-b]furans and Aminothieno[3,4-b]furans

“…11 Recently, aminobenzothieno [3,2-b]furans have been described as IKKβ inhibitors. 12 Some studies have reported the preparation of thieno [3,4-b]furan isomers, [13][14][15][16][17] mostly starting from furans in multistep syntheses, whereas thieno [3,2-b]furan isomers 11,18,19 have been prepared mainly from thiophenes.…”