Rhodium MonoPhos catalysts

Acetonitrile is another solvent that may retard the reaction. Although no cases of inhibition by acetonitrile have been described in the literature, we usually find no hydrogenation activity at all when using rhodium/MonoPhos catalysts in this solvent Presumably, this is true for most transition metal catalysts. 

The immobilization of catalysts on a solid support is a well-known approach to render a system recycleable, and this has been performed recently by the immobilization of rhodium-MonoPhos 29 a on aluminosilicate A1TUD-1. The resultant system showed high efficiency in water, and could be recycled [80]. 

In 2002, Zhou and coworkers designed and synthesized a new type of spiro phosphoamidites 1 based on spirobiindane backbone [20]. These spiro monopho sphoramidite ligands 1, especially SIPHOS (la), showed high enantioselectivities (up to 99.7% ee) in the rhodium catalyzed asymmetric hydrogenation of arylenamides (Scheme 8.4) [15]. The reaction was performed under typical conditions with rhodium catalyst, usually produced in situ from [Rh(COD)2 BP.i with 2 equiv of... 

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