Atom-efficient synthesis of 2,4,6-trisubstituted 1,3,5-triazines via Fe-catalyzed cyclization of aldehydes with NH(4)I as the sole nitrogen source

An atom-efficient, straightforward method for the synthesis of 2,4,6-triaryl-1,3,5-triazines via iron-catalyzed cyclization of aldehydes with NH(4)I as the sole nitrogen source is demonstrated. This strategy works smoothly under air atmosphere, and affords symmetrical 2,4,6-trisubstituted and unsymmetrical 1,3,5-triazines with yields from 18% to 72%. Compared to other methods, the present protocol provides a straightforward and atom-efficient approach to 2,4,6-trisubstituted 1,3,5-triazines using an inexpensive, easily available ammonium salt as the sole nitrogen source. Research into the preliminary mechanism indicates that N-benzylidenebenzimidamides are involved in this cyclization reaction.