Alkoxycarbonylation of 3,3,3-Trifluoropropyne: an Intriguing Reaction to Prepare Trifluoromethyl-Substituted Unsaturated Acid Derivatives

Abstract

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.

Aminocarbonylation of phenylacetylene catalysed by palladium acetate in combination with (2-pyridyl)diphenylphosphine and methanesulfonic acid

“…Our interest in the synthesis of ␣,␤-unsaturated amides, in particular the ones deriving from 2-arylpropenoic acids (Scheme 1, R = aryl) [4] and our concern in the use of alkyne carbonylation for the synthesis of valuable fine chemicals [5] spurred us to explore the feasibility of phenylacetylene carbonylation in the presence of amines.…”

Palladium‐Catalyzed Carbonylation Reactions of Alkenes and Alkynes

“…[85] Only moderate activity but improved catalyst stability was noted for palladium(II) complexes of (2-py)PPhA C H T U N G T R E N N U N G [CH 2 ÀA C H T U N G T R E N N U N G (thf)] IX (Figure 7) in the methoxycarbonylation of propyne. [90] Depending on the composition of the catalytic system and the reaction conditions used, either branched or linear trifluoromethyl-substituted esters were formed. [87] For example, El Ali and co-workers achieved high regioselectivity towards linear products for the conversion of terminal alkynes under neutral conditions by using a catalyst system composed of Pd II /dppb and synthesis gas (41 bar, CO/ H 2 = 1:1).…”