Esters and N,N-dialkylamides of 2-(trifluoromethyl)acrylic acid (TFMAA) through Pd-catalysed carbonylation of fluorinated unsaturated substrates

Esters and amides of 2-(trifluoromethyl)acrylic acid (TFMAA) have been synthesised by two different routes involving GO-chemistry. The alkoxycarbonylation of 2-bromo-3,3,3-trifluoropropene was carried out in the presence of PdCl2(PPh3)(2). High substrate conversions were obtained, but the yield in acrylic esters was generally low because the desired unsaturated esters reacted further adding a molecule of alcohol to the C-C double bond. The carbonylation of 2-bromo-3,3,3-trifluoropropene in the presence of secondary amines produced the corresponding unsaturated amides in high yields; the addition of the amine to the C-C double bond also occurred, but this side reaction was minimised by using secondary cyclic amines such as morpholine or piperidine. Alternatively, the acrylic esters can be obtained by hydromethoxycarbonylation of 3,3,3-trifluoropropyne using the catalytic system Pd(OCOCH3)(2)/2-pyridyldiphenylphosphine/CH3SO3H. In this process the most important side product is the isomeric crotonic ester. The regioselectivity of the reaction can be controlled to a great extent by a suitable choice of the solvent. (C) 1999 Elsevier Science B.V. All rights reserved.