Organocatalysts BINAP

Chiral palladium complexes have been employed as enantio- and diastereo-selective catalysts of a Mannich-type addition of /3-kclo esters to aldimines and imino esters, q. in a strategy which activates both reactants 28 anti-Selective direct enantioselective Mannich reactions use a BINAP-derived axi- ally chiral aminosulfonamide as organocatalyst.29... 

Scheme 12.9 Synthesis of novel cinchona alkaloid organocatalysts with modified quinoline moiety. Reagents and conditions (a) Dt-BuAD, CH2CI2, rt, 2 h, 93% (b) PhNTf2, DMAP, CH2CI2 (c) 1. Pd(OAc)2, BINAP, Cs2C03, THF, Ph2C=NH, 2. citric acid, THF, H20 (d) 3,5-(CF3)2PhNCS, THF.

Recently, Liu has developed a Bronsted acid activated trifunctional organocatalyst, based on the BINAP scaffold, that was used for the first time to catalyze aza MBH reactions between N tosylimines and MVK with fast reaction rates and good enantioselectivity at room temperature. This trifunctional catalyst containing a Lewis base, a Bronsted base and a Bronsted acid, required add activation to confer its enantioselectivity and rate improvement for both electron rich and electron deficient imine substrates. The role of the amino Lewis base of 27 was investigated and found to be the activity switch in response to an acid additive. The counterion of the acid additive was found to influence not only the excess ratio but also the sense of asymmetric induction (Scheme 13.23) [36]. 

Ru catalysts, S-BINAP also act as a organocatalysts for Mirata-Baylis-Hillman reactions involving C-H activation, e.g. in the condensation of 5-formylpytimidine and derivatives with methyl acrylate to form methyl p-hydroxy-p-(pyrimidin-5-yl)- a-methylenepropionates with moderate enantiomerie exeess at the chiral hydoxy centre [Hayase et al. Chem Commun 12711998],... 

Chiral organocatalysts were to the fore in Michael transformations prolines, thioureas, NHCs, BINAPs, and diamines, or combinations thereof. 

A BINAP-derived bifunctional thiophosphoramide gives >98% del>99% ee in Michael addition of cyclohexanones to both aryl- and alkyl-substituted nitroolefins. Imidazolylmethyl ketones undergo one-pot Michael-aldol cascade reactions with Q ,/3-unsaturated aldehydes in DCM at 20 °C using the simple organocatalyst, prolinol... 

In 2011, Hermeke and Toy synthesized phosphonium ion-tagged chiral phosphoric acids 117 and 118 bearing a BINAP core and examined them as recoverable organocatalysts in Friedel-Crafts alkylation of indoles [55], The phosphonium tag position in the catalysts was cmcial for the reaction outcome. Compound 117 with the tags at positions 3 and 3 of phosphoric acid, where they served as spaceblocking groups, failed to catalyze the reactions. However, a shift of the phosphonium ion groups to positions 6 and 6 produced efficient and enantioselective... 

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