Specific cross-dimerization of terminal alkynes via Pd/TMEDA catalysis

The cross-dimerization of terminal alkynes is the most straightforward and attractive approach to differently substituted 1,3-enynes, which are vital structural motifs in natural products, biologically active compounds, and organic functional materials, etc. However, due to the inherent issues of the stereo-, regio-, and chemoselectivity, the strategy is less explored and remains problematic in substrate scope, selectivity, and screening of catalytic system, etc. Herein, a specific cross-dimerization of terminal alkynes is developed under Pd/TMEDA catalysis, which produces a series of gem-1,3-enynes (58 examples) in totally moderate to high yields with outstanding functional group tolerance. A cyclopalladium compound might be the key imtermediate, which performs anti-addition-carbometallation, and leads to the exclusive cross-selectivity. The unprecedented features of the reaction, such as anti-addition-carbometallation, easy control of selectivity, wide range of the donor alkynes, and very simple catalytic conditions, allow it not only a facile and functionally diverse synthesis of 1,3-enynes, but also a substantial progress for the textbook reaction.

Automated summary

In this study, a specific cross-dimerization of terminal alkynes is developed under Pd/TMEDA catalysis, which produces a series of gem-1,3-enynes with different functional group tolerance in moderate to high yields. The reaction features anti-addition-carbometallation, easy control of selectivity, wide range of donor alkynes, and simple catalytic conditions.