Bite angles substrates

The catalytic hydroformylation of alkenes has been extensively studied. The selective formation of linear versus branched aldehydes is of capital relevance, and this selectivity is influenced by many factors such as the configuration of the ligands in the metallic catalysts, i.e., its bite angle, flexibility, and electronic properties [152,153]. A series of phosphinous amide ligands have been developed for influencing the direction of approach of the substrate to the active catalyst and, therefore, on the selectivity of the reaction. The use of Rh(I) catalysts bearing the ligands in Scheme 34, that is the phosphinous amides 37 (R ... 

UlluPHOS [43, 44], catASium M [48, 95], Kephos [45, 96] and Butiphane [97] - four ligand systems which possess larger P-Rh-P bite angles than DuPhos [44, 46, 97] - all achieved enantioselectivities >95% when used in the hydrogenation of some model substrates. Much importance has been attached to P-Rh-P bite angles larger than the parent DuPhos system. It is believed that the pos-... 

Stereoselectivity in hydroformylation reactions, as a result of the supporting ligand set (e.g. large bite angle diphosphines or chiral diphosphines) or by stereocontrol of the substrate has also been discussed by Breit. Rhodium complexes supported by large bite angle diphosphines such as bisbi, biphephos and xantphos, shown in Scheme 10, are now well-established... 

Moderate enantioselectivity in terms of differentiation between the enan-tiotopic olefin functionality of prochiral ene substrate with planar symmetry was observed by using a chiral palladium complex. The use of a chiral bidentate ligand with a large bite angle [66] is effective for this type of enantioselective catalytic metallo-ene cyclizations. 

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