One-pot condensation of 2-arylpropenes with formaldehyde and ammonium chloride: the synthesis of aryl substituted pyridines and 5,7,11-trioxa-1-azatricyclo[7.3.1.03,8]tridecanes

A mixture consisting of 2-arylpropene 1 or 2, formaldehyde and ammonium chloride condenses in a one-pot manner to yield 5,7,11-trioxa-1-azatricyclo [7.3.1.0^3,8]tridecanes 3 or 4. In the presence of manganese dioxide the reaction leads to 4-arylpyridines 5 or 6.