Mercuration of thiophene-2-carboxylic: acid, 2-thienylethanoic acid and 3-(2-thienyl)alanine: preparation and spectral characterization

Thiophene-2-carboxylic acid, 2-thienylethanoic acid and 3-(2-thienyl)alanin e were mercurated with mercury(II) chloride in aqueous media in the presenc e of sodium acetate trihydrate. Mono- and di-mercurated products were obtai ned, depending on the reaction conditions. When mercury(II) acetate was use d as the mercuration agent a mixture of mono- and dimercurated products was obtained, The chemical formulae and the structures of the isolated compoun ds were deduced from elemental chemical analysis and IR spectra. In the cas e of soluble products the site and degree of mercuration were determined on the basis of H-1 and C-13 NMR spectra, In monomercurated thiophene-2-carbo xylic acid, 2-thienylethanoic acid and 3-(2-thienyl)alanine the H-5 signal was absent, which together with the large downfield shift of the correspond ing 13C Signal (ca 24 and 21 ppm) confirmed that mercuration took place at the C-5, Two- and three-bond Hg-199-C-13 satellite couplings at C-4 and C-3 as well as four-bond Hg-199-H-1 coupling at H-4 were also revealed. Copyri ght (C) 2000 John Wiley & Sons, Ltd.