Cooperative amino catalyst-based

Amino Catalyst-Based Cooperative Catalysis with Multifarious Co-Catalysts 11343... 

Peters applied the cooperative activation by a soft bimetallic catalyst 220, a hard Br0nsted acid, and a hard Bronsted base to the formation of highly enantio-enriched, diastereomerically pure masked a-amino acids 225 bearing adjacent tetrasubstituted and tertiary carbon stereocenters on the basis of a domino azlactone formation/Michael addition reaction starting from N-benzoylated amino acids 221 and a,P-unsaturated ketones 180 (Scheme 11.47). Since the activated catalyst was stable toward acetic anhydride, the in situ formation of azlactones 223 could be achieved through O-acylation with acetic anhydride of N-benzoylated amino acids... 

Cooperative dual activation of both the monomer and the initiator/polymer chain ends can be operative with specific catalysts (e.g., TU-amino derivatives, TBD, or even DMAP) as a means to tri er the ROP of cydic esters. Here also, analogies can he foimd with some metal-based catalysts which have been su ested to behave by such a dual activation (Scheme 6). Using true organic catalysts for ROP implies that an electrophilic moiety (typically proton) activates the heteroatom of the... 

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