title: Stereoselectivity of additions to N-methyl acetonitrilium fluorosulfonate.
abstract: Alkoxy-N-methyl-acetiminium salts were prepared by addition of CH3OH and C2H5OH to N-methyl acetonitrilium fluorosulfonate at low temperature. Analysis of the 5J(HH) and 3J(13C–H) coupling constants in the NMR spectra showed an anti addition with a diastereoselectivity of >95%. Deprotonation of these salts with (Z)-configuration gave the corresponding N-methyl-alkoxyacetimines with very high (E)-configuration. Upon protonation at −78 °C, these iminoesters gave the corresponding alkoxy-N-methyl-acetiminium salts with (E)-configuration. Computational analyses of the iminoesters and the corresponding iminium cations including the conformations give insight into the relative stability. Nitrilium salts can be used as reagents, exemplified by some esterifications between simple acids and alcohols.
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland. reinhart.keese@ioc.unibe.ch
authors.forename: Reinhart
authors.initials: R
authors.lastname: Keese
authors.forename: François
authors.initials: F
authors.lastname: Berdat
authors.forename: Piero
authors.initials: P
authors.lastname: Macchi