Petasis reactions organocatalyst

An enantioselective variant of Petasis reaction catalyzed by the chiral biphenol 10 was applied to the synthesis of optically active amines 11 (eq 7) (32). Enantioselective addition ofalkyne catalyzed by the chiral copper-phosphine ligand in MCR offers a practical pathway to obtain homochiral propargylamines like 12 (eq 8) (33). The last decade has also wimessed the emergence of organocatalysts, derived from natural products like amino acids (with more emphasis... 

In this pivotal example, the authors have demonstrated the ability of bifunctional thiourea organocatalyst 28 to provide the sufficient activation of organoboronic acids in the Petasis reaction using quinolones 26, as a powerful method for the enantio- and regioselective synthesis of 1,2-adducts 29 against the possibility of generation of 1,4-adducts (Table 4.1) [28],... 

The Petasis reaction is a multicomponent condensation occurring between boronic acids, amines and aldehydes. The asymmetric version of this reaction is very attractive for the synthesis of chiral a-amino acids.In this context, Schaus and Lou reported the use of chiral biphenols as organocatalysts for the asymmetric Petasis reaction of ( )-diethyl styrylboronate with secondary amines and ethyl glyoxylate. The corresponding a-amino esters were obtained in high yields and enantioselectivities of up to 97% ee by using a vaulted biaryl phenol such as (5)-VAPOL as the organocatalyst in the presence of 3-A molecular sieves (Scheme 2.59). 

The chiral thiourea organocatalyst for the catalytic enantioselective Petasis reaction... 

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