An enantioselective Rh -catalyzed conjugate addition reaction of α-substituted β-nitroacrylates with various arylboronic acids by using chiral Rh diene catalysts is described for the first time. The addition reaction proceeds under mild conditions in a range of common organic solvents and additives, and it affords the corresponding quaternary-carbon-containing α,α-disubstituted β-nitropropionate products in up to 63 % yield and 99 % ee. Reaction of either (E)- or (Z)-β-nitroacrylates provided the same enantiomer of the product, and a range of esters and aryl groups were tolerated. To demonstrate the utility of the method, ethyl (R)-1,1-methyl-1-phenyl-3-nitropropionate, prepared herein, was converted to the non-proteinogenic β -amino acid, (R)-2-(aminomethyl)-2-phenylpropanoic acid, and to the β -lactam, (R)-3-methyl-3-phenylazetidin-2-one. In addition, a tripeptide, which comprised l-phenylalanine, l-alanine, and β -amino acid 7, was also synthesized.

The preparationo fc hiral 4-aryl-2-pyrrolidones by conjugate addition catalyzed by ar hodium(I) complex, comprising the chiral bicyclo[2.2.1] diene ligand 1e,i sr eported. The reaction of various arylboronic acids and a,bunsaturated g-lactams 2 bearing various N-substituents proceeds in ah ighly stereoselective fashion (93-99.5 % ee) even in the presence of only 0.5 mol %o ft he Rh catalyst affording the corresponding addition products in 31-99 % yield.