An Effective Synthesis of 2-Trifluoromethyl- or 2-(1,1-Difluoroalkyl)thiophenes

Synthesis of aromatic heterocycles

“…42 α-Fluoroalkylcarbonyl compounds 33, which have previously been used in the synthesis of fluoroalkyl substituted pyrazoles and pyrimidines, gave 2-(α-fluoroalkyl)thiophenes on reaction with methyl mercaptoacetate and sodium methoxide (Scheme 15). 43 Relatively few new routes to benzothiophenes have been described in the period under review. The route to benzofurans described by Katritzky and co-workers has also been used as a one pot synthesis of benzothiophenes, the thioethers analogous to 24 being intermediates.…”

Synthesis and mesomorphic properties of 1,1-difluoroalkyl-substituted biphenylthienyl and terphenyl liquid crystals. A comparative study of mesomorphic behavior relative to alkyl, alkoxy and alkanoyl analogsElectronic supplementary information (ESI) available: experimental details for compounds 4, 9, 10, 12, 15–19, 25–39, 45 and 49. See http://www.rsc.org/suppdata/jm/b1/b102059p/

“…1-Bromo-4-pentylbenzene (22) was obtained by Friedel-Crafts acylation of bromobenzene using valeryl chloride followed by Wolff-Kishner reduction of the resulting ketone. 32 1-Bromo-4-butoxybenzene (23) was obtained by etherification of 4-bromophenol with 1-bromobutane. 37 The synthesis of terphenyl 36 was carried out via coupling of substituted phenylboronic acid 10 with bromobiphenyl building block 40 (Scheme 6).…”

“…Even in nonliquid crystal chemistry there are remarkably few examples of the synthesis of (1,1-difluoroalkyl)arenes and, even then, compounds of general structure ArCF 2 (CH 2 ) n CH 3 when nw1 are not known as far as we have been able to ascertain. [19][20][21][22][23] Lateral core substituents have been used extensively to alter the mesomorphic behavior of liquid crystalline compounds. Lateral core fluorine substitution has proven to be especially useful in this area due to the relatively small size and high electronegativity of the fluorine atom.…”

Preparation of 4-Hydroxy-2-trifluoromethylthiophene: A Novel Bioisostere of α,α,α-Trifluoro-m-cresol

“…Fractional distillation (60-62°C, 2.5 mm) through a Vigreux column (30 cm) afforded 378 g (63%) of 6. 20 …”