Cycloaddition products have been prepared from 3-hydroxypyridinium betaines containing N-carbamoyl, N-phenyl-thiomethyl, N-thiadiazoyl, N-benzylideneamino-, and N-4-pyridyl substituents.
                                    环加成产品已经从含有3- hydroxypyridinium
甜菜碱制备Ñ -
氨甲酰基,Ñ苯基
硫代甲基,Ñ -thiadiazoyl,Ñ -benzylideneamino-和Ñ -4-
吡啶基的取代基。