Preparation and Evalutation
A few years ago, one [1] of us described the first multi-component synthesis of N-(1 -haloalkyl) pyridinium halides from a thionyl halide, pyridine, and an aldehyde (Scheme 1). Since that time, we [2- 4] have widely demonstrated that such salts can be considered as valuable synthetic equivalents of the starting aldehydes for the preparation of various classes of nitrogen heterocycles.