Asymmetric epoxidation of cis-alkenes mediated by iminium salts: highly enantioselective synthesis of levcromakalim.
[reaction: see text] A range of cis-substituted olefins has been epoxidized with a new dihydroisoquinolinium salt catalyst, using tetraphenylphosphonium monoperoxysulfate as the stoichiometric oxidant, giving ee's of up to 97%. The reaction has been used as the key step in an enantioselective synthesis of the antihypertensive agent levcromakalim.
Page
Philip C Bulman
PC
Department of Chemistry, Loughborough University, Loughborough, Leicestershire LE11 3TU, England. p.c.b.page@lboro.ac.uk
Buckley
Benjamin R
BR
Heaney
Harry
H
Blacker
A John
AJ