Asymmetric 1,3-dipolar cycloaddition, silver

Using a related cycloaddition protocol, Schreiber found that the chiral P,N-ligand QUINAP (121) exhibited comparable high enantioselectivity in silver-catalyzed dipolar cycloadditions (Equation 6) [98], The highest asymmetric induction was observed for tert-hutyl acrylate (119) with aromatic imino esters such as 118. The process shows a wide substrate scope, as the transformation was tolerant both of a-substitution in 118 and of /3-substitution of the acrylate dipolarophile 119. Carreira has crafted and studied the use of a family of atropisomeric P,N-ligands, as exemplified by 122 [99]. 

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