Catalytic enantioselective 1,3-dipolar cycloadditions of nitrones with propioloylpyrazoles and acryloylpyrazoles induced by chiral π-cation catalysts

Akira Sakakura; Masahiro Hori; Makoto Fushimi; Kazuaki Ishihara

doi:10.1021/ja1081603

Catalytic enantioselective 1,3-dipolar cycloadditions of nitrones with propioloylpyrazoles and acryloylpyrazoles induced by chiral π-cation catalysts

J Am Chem Soc. 2010 Nov 10;132(44):15550-2. doi: 10.1021/ja1081603.

Authors

Akira Sakakura¹, Masahiro Hori, Makoto Fushimi, Kazuaki Ishihara

Affiliation

¹ EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8603, Japan.

PMID: 20958041
DOI: 10.1021/ja1081603

Abstract

A chiral copper(II) complex of 3-(2-naphthyl)-l-alanine amide successfully catalyzes the enantioselective 1,3-dipolar cycloaddition reaction of nitrones with propioloylpyrazole and acryloylpyrazole derivatives. The asymmetric environment created by intramolecular π-cation interaction gives the corresponding adducts in high yields with excellent enantioselectivity. This is the first successful method for the catalytic enantioselective 1,3-dipolar cycloaddition of nitrones with acetylene derivatives. The 1,3-dipolar cycloadducts can be stereoselectively converted to β-lactams via reductive cleavage of the N-O bond using SmI(2).