2:1 versus 1:1 Coupling of Alkylacetylenes with Secondary Amines: Selectivity Switching in 8-Quinolinolato Rhodium Catalysis

Both 2:1 and 1:1 couplings of alkylacetylenes with secondary amines were achieved using 8-quinolinolato rhodium catalysts and CsF. The 2:1/1:1 selectivity was switched by choosing the reaction solvent. In DMA, an unprecedented 2:1 coupling reaction of alkylacetylenes with amines proceeded to give 2-aminodiene products. One-pot 2:1 coupling/reduction provided rapid access to various allylamines, while one-pot coupling/hydrolysis gave enonesas products. In toluene, anti-Markovnikov hydroamination occurred under relatively mild conditions to give 1:1 coupling products.

Automated summary

Utilizing 8-quinolinolato rhodium catalysts and CsF, the coupling of alkylacetylenes with secondary amines in both 2:1 and 1:1 ratios was achieved. The solvent choice can switch the selectivity between 2:1 and 1:1 ratios, leading to different products under different reaction conditions.Additionally, anti-Markovnikov hydroamination reactions in toluene resulted in 1:1 coupling products under relatively mild conditions.