- Alkoxycarbonylation of 3,3,3-Trifluoropropyne: An Intriguing Reaction to Prepare Trifluoromethyl-Substituted Unsaturated Acid Derivatives
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The addition of CO and methanol to 3,3,3-trifluoropropyne is catalysed by Pd(OAc)2 in the presence of (6-methylpyrid-2-yl)diphenylphosphine and CH3SO3H. The main products of the reaction are the methyl esters of 2-(trifluoromethyl)propenoic acid 1 and of 3-(trifluoromethyl)propenoic acid 2 (4,4,4-trifluorobut-2-enoic acid). The regioselectivity of the reaction can be controlled to a great extent by a suitable choice of the composition of the catalytic system and the reaction conditions. Thus, 1 can be obtained in 93% yield by using P(CO) = 20 atm and high ligand/Pd and acid/Pd ratios. On the other hand, selectivity up to 85% in 2 can be achieved using P(CO) = 80 atm and a low ligand/Pd ratio together with a high acid/Pd ratio. The reaction mechanism is also discussed.
- Scrivanti,Beghetto,Matteoli
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p. 543 - 547
(2007/10/03)
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