Palladium(II)‐catalyzed catalytic aminocarbonylation and alkoxycarbonylation of terminal alkynes: regioselectivity controlled by the nucleophiles

Abstract

The aminocarbonylation and alkoxycarbonylation reactions of terminal alkynes took place smoothly and efficiently using a catalyst system Pd(OAc) 2 -dppb-p-TsOH-CH 3 CN-CO under relatively mild experimental conditions. The catalytic system was tested and optimized using two different nucleophiles: alcohols and amines. Phenylacetylene (1a) was considered as an alkyne along with diisobutylamine (2b 1 ) and methanol (2c 1 ) as nucleophiles. The results showed significant differences in the conversion of 1a and in the selectivity towards the gem or trans unsaturated esters or amides with these nucleophiles. The effects of the type of palladium catalysts, the type of ligands, the amount of dppb and the solvents were carefully studied. With diisobutylamine (2b 1 ), excellent regioselectivity towards the 2-acrylamides (gem isomer, 3ab 1 ) was almost always observed, while trans-α,β-unsaturated esters 4ac 1 was the predominant product with methanol (2c 1 ) as a nucleophile. This remarkable sensitivity in the selectivity of the reaction indicates two different possible mechanistic pathways for these carbonylation reactions.

Nonclassical Routes for Amide Bond Formation

“…Later on, El Ali and co-workers have proposed a reaction mechanism pathway based on DFT calculations for the aminocarbonylation of propyne. 236,237 Ionic liquid [bmin][Tf 2 N] has shown to be a good reaction medium for the synthesis of acrylamides from terminal aryl and alkyl acetylenes with primary and secondary amines. 238 Interestingly, no acidic cocatalyst was necessary [e.g., amine/ alkyne molar ratio 5:1, Pd(OAc) 2 (3 mol %), dppp (6 mol %), CO (14 atm), 110 °C, 22 h].…”

“…Later on, El Ali and co-workers have proposed a reaction mechanism pathway based on DFT calculations for the aminocarbonylation of propyne. , …”

Synthesis, Characterization, and Reaction Studies of Pd(II) Tripeptide Complexes

“…Carbonylation reactions are typically performed using CO in conjunction with various monomers, including olefins [ 52 , 53 , 54 ] and alcohols [ 55 ] under high pressure to yield various carboxylic acid derivatives. In order to avoid the use of carbon monoxide as C 1 -feedstock, CO surrogates may be used.…”

Development of Bulk Organic Chemical Processes—History, Status, and Opportunities for Academic Research

“…Transition metal-catalyzed carbonylation reactions represent an important toolbox to produce aldehydes and a variety of carboxylic acid derivatives. Hence, using starting materials such as olefins, [80][81][82][83] alcohols, 84 alkyl or aryl halides 85 the corresponding esters, acids, aldehydes, amides, and C 1extended alcohols 86 are straightforwardly available depending on the type of carbonylation reaction. Industrially most relevant are carbonylation's of olefins, which have been pioneered both by industrial chemists Otto Roelen (hydroformylation) 87,88 and Walter Reppe (hydroxyl-and alkoxycarbonylation) 89 .…”