Styrene and diazo esters react in the presence of copper(II) trifluoromethanesulfonate (1 mol%) and (1S,2S)-N,N′-di(mesitylmethyl)-1,2-diphenyl-1,2-ethanediamine (2 – 3 mol%) to give 2-phenyl-1-cyclopropanecarboxylates in good to excellent optical yields. This reaction has been applied tov the synthesis of chrythanthemic acid.
Asymmetric copper-catalyzed cyclopropanation of trisubstituted and unsymmetrical cis-1,2-disubstituted olefins: modified bis-oxazoline ligands
作者:Richard E. Lowenthal、Satoru Masamune
DOI:10.1016/0040-4039(91)80110-r
日期:1991.12
The Cu(I) complexes of newbis-oxazolines (3–7) prepared from the corresponding amino alcohols and malono-bis-imidate exhibit high enantioselectivity of up to 94 %ee in the catalytic cyclopropanation of trisubstituted and unsymmetrical cis-1,2-disubstituted olefins. New diazoacetate reagents have also been developed giving high trans/cis ratios of up to 99:1 trans.