The Renaissance of an Old Problem: Highly Regioselective Carboxylation of 2‐Alkynyl Bromides with Carbon Dioxide

Abstract

A steric effect-controlled, zinc-mediated carboxylation of different 2-alkynyl bromides under an atmospheric pressure of CO2 has been developed by careful tuning of different reaction parameters, including the metal, solvent, temperature, and additive. 2-Substituted 2,3-allenoic acids were afforded from primary 2-alkynyl bromides, whereas the carboxylation of secondary 2-alkynyl bromides yielded 3-alkynoic acids in decent yields. A rationale for the observed regioselectivity has been proposed.

Regioselective Ni-Catalyzed Carboxylation of Allylic and Propargylic Alcohols with Carbon Dioxide

“…Recently, the cobalt-catalyzed carboxylation of propargylic acetates was elegantly developed by Tsuji and co-workers . However, to the best of our knowledge, the direct carboxylation of propargylic alcohols has not yet been described in the literature . Surprisingly, carboxylation of propargylic alcohols occurs smoothly under similar conditions via sequential hydrogenation and carboxylation (Scheme ).…”

Enantioselective Construction of Tertiary α-Alkyl Fluoride via BTM-Catalyzed Fluorination of α-Alkynyl-Substituted Acetic Acids

“…Values of optical rotation were measured on a Rudolph Automatic Polarimeter A21101 at the wavelength of the sodium D-line (589 nm). The branched alkynyl acids 1 were synthesized by a known protocol …”

Synthesis of Pyrrolidin-5-one-2-carboxamides through Cyclization of N-Substituted-2-alleneamides

“…All reagents and solvents were purchased commercially and used as received without further purification, except those listed below: dry DCM and chloroform were prepared by distillation over CaH 2 and P 2 O 5 , respectively, under nitrogen. Allenic acids 4a and 4b were prepared according to the reported procedures . All reactions were monitored by TLC over Merck silica gel 60-F254 plates and UV light of 254 nm for detection.…”

“…The presence of other functional groups with the allene structure may further contribute to the allene’s synergistic activity. Alkoxyallene, allenol, allenic ester, allenic ketone, and allenoic acid derivatives are all instances of this group that were used as multi-functional compounds that were employed as starting materials for the synthesis of organic compounds. Allenoic acids can be used in the Ugi reaction to synthesize allenamides and pseudopeptides.…”