Palladium complexes guanidines

Enantioselective a-animation of carbonyl compounds has been promoted by l-azetidinecarboxylic acid,159 axially chiral guanidine derivative,160 and chiral palladium complexes.161... 

Palladium(II) acetate reacts with N,N, N"-triphenylguanidine ( = HTpg) in warm benzene to form a bis-adduct which, under more forcing conditions, converts to the novel dinuclear guanidinate-bridged complex [Pd(/L-Tpg)... 

Pd(0)/phosphine complexes, or their precursors, in the presence of a suitable co-base, have also been shown to promote, in good yields (66-100%), the formation of allylic carbamates from various primary and secondary aliphatic amines, pressurized C02 and allylic chlorides, in THF, at ambient temperature [87a]. The choice of the added co-base (Base), used for generating the carbamate salt RR NC02 (BaseH)+, was found to be critical for high yields of O-allylic urethanes. The use of a guanidine (CyTMG) or amidine (DBU) base was optimal for this system (see also Section 6.3.1). ft is assumed that this chemistry passes catalytically through a mechanism similar to that illustrated in Scheme 6.19. This involves nucleophilic attack by carbamate anion on a (tt-allyl) palladium species, formed by the oxidative addition of the allylic chloride to a palladium(O) intermediate. 

Yang, H., Han, X., Ma, Z., et al. (2010). Palladium-Guanidine Complex Immobilized on SBA-16 A Highly Active and Recyclable Catalyst for Suzuki Coupling and Alcohol Oxidation, Green Chem., 12, pp. 441 51. 

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