Asymmetric Conjugate Additionof Arylboronic Acids to Enones Catalyzed by Rhodium-MonodentatePhosphoramidite Complexes in the Presence of Bases

摘要

Rhodium(I)-catalyzed 1,4-addition of arylboronic acids to α,β-unsaturatedcarbonyl compounds was carried out in the presence of a chiral phosphoramiditeligand based on (R)-binol and dialkylamines.The reaction was significantly accelerated in the presence of abase such as KOH and Et3N, allowing the reaction to becompleted within 6 hours at 50 °C. The additionto 2-cyclohexenone achieved enantioselectivities up to 99%,though they were less effective for 2-cyclopentenone (79% ee),2-cycloheptenone (77% ee) and acyclic enones (31-43% ee).