AN UNEXPECTED RING-OPENING IN THE REISSERT REACTION ON 2,3-DIPHENYLQUINOXALINE-N-OXIDE.

Article abstract of DOI:10.1016/S0040-4020(01)85794-X

When quinoxaline-N-oxide 1 is reacted with KCN and benzoyl chloride in water (the Reissert reaction) or methanol, the products are 2-, 5- and 6- chloroquinoxaline (the latter being the major product: 42+/-6percent) and small amounts of 2-cyanoquinoxaline.Using three equivalents of trimethylsilyl cyanide instead of KCN, and dichloromethane as the solvent, leads to a 72percent yield of 2-cyanoquinoxaline.The reaction of trimethylsilyl cyanide and benzoyl chloride with 2,3-diphenylquinoxaline-N-oxide 2 leads to an unexpected ring-opening product 13; its structure is based on spectroscopic data and on an X-ray crystallographic analysis.