Organocatalytic synergic

Among all the possible approach to polysubstimted cyclohexane derivatives, Dixon et al. proposed a further and very elegant alternative approach wherein the asymmetric organocatalytic cascade reaction reties on the synergic action of a bifunctional base/Br0nsted acid catalyst 158 and a cyclic secondary amine (5)-76 (Scheme 2.49) [77]. 

Scheme 26.7 Synergic organocatalytic addition developed by Nishibayashi.

List has developed the concept of asymmetric counter-ion directed catalysis and applied it in organocatalytic transformations. One of the first pioneering studies in the synergic use of organocatalyst and transition metal was the combination of a Pd(0) catalyst with a chiral phosphoric acid in a highly enantioselective Tsuji-Trost type a-allylation of branched aldehydes (Scheme 26.12) [81]. 

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