Hydro-oxycarbonylation is an attractive atom-economical reaction that produces valuable enol esters from the simple addition of carboxylic acids and alkynes. These enol esters are useful building blocks for synthesising complex biologically active molecules. Yet, despite the efficiency of this reaction, methods developed so far have been concentrated on using precious metal catalysts such as ruthenium,[1] with rare examples relying on gold or iridium for catalysis.[2][3] To expand the practicability of this simple effective reaction, we have developed a novel catalytic system that employs the use of copper, a low-cost earth abundant metal, as catalyst. The difficulty of this reaction lies in the need for good regiocontrol as the use of terminal alkynes can produce three different products, namely the Markovnikov product, the anti-Markovnikov (Z) and the anti-Markovnikov (E) isomers. (Scheme 1) To resolve this problem, we have developed two complementary systems that rely on different copper catalysts and ligands to obtain good regioselectivity for both the Markovnikov product 3a (yield ≤ 94%, 3a:3b ≤ 92:8) and the anti-Markovnikov product 3b. (yield ≤ 89%, 3b:3a ≤ 96:4) The new method covers a wide scope while illustrating good functional group tolerance to give enol esters in good to high yields.

Copper-catalyzed hydro-oxycarboxylation of terminal alkynes

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.