Pyridine N-Oxide → 3-(4-Methylphenyl)pyridine-2-carbonitrile

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Reaction Steps

Synthetic Scheme XXVIII shows the 4-step preparation of the alkylating reagent 2-cyano-3-(4-bromomethylphenyl)pyridine (79) from 3-bromopyridine (80) (Aldrich). In step 1, the pyridine 80 was reacted with hydrogen peroxide in acetic acid at reflux to give the pyridine N-oxide 81. In step 2, the N-oxide 81 was converted to 3-bromo-2-cyanopyridine (82) by reaction with trimethysilylcyanide and triethyl anine in acetonitrile at reflux. In step 3, the nitrile 82 was coupled with 4-methylphenylboronic acid (56) (Scheme XXIV) using Snieckus conditions (Scheme XIII) to give 2-cyano-3-(4-methylphenyl) pyridine (83). In step 4, 83 was brominated with NBS/AIBN in carbon tetrachloride at reflux to give the desired alkylating reagent 79. ##STR91##

Provenance & Evidence