Photostimulated Reactions of 2-Bromopyridine and 2-Chloroquinoline with Nitrile-Stabilized Carbanions and Certain Other Nucleophiles

Article abstract of DOI:10.1021/jo00162a020

Potassiophenylacetonitrile (2) reacts with 2-bromopyridine (1) and 2-chloroquinoline (4) via the S_RN1 mechanism when the reactants are exposed to near-UV light in liquid NH3.Potassioacetonitrile (6) reacts similarly with 1 and 4 upon photostimulation; however, the photo-S_RN1 reaction with 1 is accompanied by S_NAr2 amination which becomes the major reaction in the dark or in the presence of di-tert-butyl nitroxide.Substrate 4 undergoes competing S_NAr2 amination with amide ion to form 2-aminoquinoline (10) and S_N(ANRORC) reactions with both amide ion and carban ion 6 to form 3-methylquinazoline (11) and 2-methyl-3-cyanoquinoline (12), respectively.Formation of 12 becomes the major pathway in reactions between 4 and 6 carried out in the dark. 4-Picolylpotassium (14) reacts with 1, 4, and 4-bromopyridinium chloride (16) under photostimulation to form the appropriate dihetarylmethanes, along with the corresponding amino heterocycles.Amination of 1, 4, and 16 predominates when these reactions are carried out in the dark.Ammonium thiophenoxide (20) undergoes a slow photo-S_RN1 reaction with 1 but fails to produce the expected 2-quinolyl phenyl sulfide with 4 after 2 h of irradiation.Potassium salts of acetylene, phenylacetylene, and phthalimide do not react with 1 or 4 after 2 h of exposure to near-UV light.