Amalgam (Na.Hg) reduction of some 4‐Substituted‐2‐amino‐3,5‐dicyano‐6‐methoxypyridines. New evidence regarding the oxidation step in their synthesis

Abstract

The amalgam (Na.Hg) reduction of some 4‐substituted‐2‐amino‐3,5‐dicyano‐6‐methoxypyridines 3 results in the formation, in high yields of 3,4‐dihydropyridines 2. Highfield 1H and 13C nmr studies provide unambiguous support for the structures proposed. The synthesis of C‐4 deuterium labeled dihydropyridine 2c‐D, by this procedure, let us understand the role played by this dihydropyridines as intermediates in the necessary oxidation path into the synthesis of pyridines 3 from malononitrile and benzylidenemalononitriles 1 in methanol/sodium methoxide.

Synthesis, X-ray structure and NMR data of 12-amino-15-phenyl-2,5,8-trioxa-13-azabicyclo[9.2.2]pentadeca-1(14),12- diene-11,14-dicarbonitrile

“…Cyclic voltammetric data on the mercury cathode of the 2-amino-6-methoxy-4-phenylpyridine-3,5-dicarbonitrile 14 showed two peaks in the cathodic region at 21.88 and 22.20 V (vs. Ag/Ag + ), § which make this compound susceptible to reduction by amalgam (Na•Hg). 15 On the basis of this behavior, we have developed a molecular system containing a latent nucleophilic pyridine ring moiety, switched on by electro-chemical reduction, and an electrophilic center moiety linked by oxyethylene bridges.…”