Mechanism of the von Braun amide degradations with carbonyl bromide or phosphorus pentabromide

Nitrilium ions – synthesis and applications

Access to both stable and transient nitrilium ions and the use of these synthons in the organic synthesis of imines and a large spectrum of heterocycles and transition metal complexes are succinctly summarized.

Stereoselectivity of additions to N-methyl acetonitrilium fluorosulfonate

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.