Regioselectivity with Hemispherical Chelators: Increasing the Catalytic Efficiency of Complexes of Diphosphanes with Large Bite Angles

Control through molecular pockets: Calixarene‐derived diphosphites provide effective hemispherical crowding about catalytic centers. When used in the palladium‐catalyzed alkylation of cinnamyl acetate, regioselectivities higher than 98 % in favor of the linear product are observed. In the rhodium‐catalyzed hydroformylation of styrene, these diphosphites lead to phenylpropionaldehyde with selectivities as high as 76 %.