Simple Synthetic Approach to N -(Pyridin-2-yl)imidates from Nitrostyrenes and 2-Aminopyridines via the N -(Pyridin-2-yl)iminonitriles as Intermediates.

A facile, green, synthetic protocol of several substituted N -(pyridin-2-yl)imidates from nitrostyrenes and 2-aminopyridines via the corresponding N -(pyridin-2-yl)iminonitriles as intermediates is reported. The reaction process involved the in situ formation of the corresponding α-iminontriles under heterogeneous Lewis acid catalysis in the presence of Al 2 O 3 . Subsequently, α-iminonitriles were selectively transformed into the desired N -(pyridin-2-yl)imidates under ambient conditions and in the presence of Cs 2 CO 3 in alcoholic media. Under these conditions, 1,2- and 1,3-propanediols also led to the corresponding mono-substituted imidates at room temperature. The present synthetic protocol was also developed on one mmol scale, providing access to this important scaffold. A preliminary synthetic application of the present N -(pyridin-2-yl)imidates was carried out for their facile conversion into the N -heterocycles 2-(4-chlorophenyl)-4,5-dihydro-1 H -imidazole and 2-(4-chlorophenyl)-1,4,5,6-tetrahydropyrimidine in the presence of the corresponding ethylenediamine and 1,3-diaminopropane.