SYNTHESIS OF SOME HIGHLY FUNCTIONALIZED THIOPHENE-3-CARBOXYLATES AND ALCOHOLS

Citation
Gm. Coppola et al., SYNTHESIS OF SOME HIGHLY FUNCTIONALIZED THIOPHENE-3-CARBOXYLATES AND ALCOHOLS, Journal of heterocyclic chemistry, 33(3), 1996, pp. 687-696
Citations number
12
Categorie Soggetti
Chemistry Inorganic & Nuclear
ISSN journal
0022152X
Volume
33
Issue
3
Year of publication
1996
Pages
687 - 696
Database
ISI
SICI code
0022-152X(1996)33:3<687:SOSHFT>2.0.ZU;2-T
Abstract
Highly functionalized thiophenes are prepared by two methods. The firs t uses a lithium-halogen exchange reaction on a trisubstituted 5-bromo thiophene 25 to generate the corresponding 5-lithiothiophene 26 which is then reacted with either dimethylformamide or formaldehyde to give the 5-formyl 28 or 5-hydroxymethylthiophene derivative 31 in good yiel ds. These are further transformed to other tetrasubstituted thiophenes . The second method assembles the thiophene ring from three components : a benzyl mercaptan, an aldehyde, and a vinylphosphonate 10. Thus, th e benzyl mercaptan is dilithiated then reacted with an appropriate ald ehyde to afford a 2-mercapto-2-phenylethanol derivative 37. Michael ad dition of 37 to 10 followed by oxidation of the hydroxyl group furnish es ketophosphonate 39. An intramolecular Wittig-type reaction produces the thiophene skeleton.