TangPhos

Itaconic acids are reduced in very high enantiomeric excesses (>97%) with Rh-TangPhos catalysts 658 Itaconic acid is reduced in 99.5% ee with the sugar-derived ferrocenyl phosphine 123.659... 

The 1-t-butylphospholane sulfide intermediate to TangPhos was also used to prepare the P,N ligands 48 by reacting the lithium complex with C02 and then oxazoline formation with a range of chiral amino alcohols [69b, 74]. The Ir complexes of these ligands have been successfully used in the reduction of / -methylcinnamic esters (80-99% ee) and methylstilbene derivatives (75-95% ee), a particularly challenging class of unfunctionalized olefins [4 c]. 

Several phospholane-based ligands have shown a wide substrate scope beyond the standard examples represented in Table 24.2. Both Et-FerroTANE 61 [147] and TangPhos 46 [69 b, 71] have been successfully applied to a diverse range of methyl and ethyl />-aryl-dehydroamino acids containing various aromatic substituents, whilst catASium M 20a [95] has been used for the reduction of numerous yS-alkyl-dehydroamino acid esters. 

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