Solvent effects on the asymmetric Pauson-Khand-type reaction by rhodium

Coordinating solvents, such as THF, provided a faster reaction and better selectivity in asymmetric Pauson-Khand-type reaction by rhodium than non-coordinating solvents, such as toluene. We found that these beneficial effects are due to a significant increase of more reactive catalysts 3 or 4 than 5 in a coordinating solvent.