AN IMPROVED PROCESS FOR THE PREPARATION OF QUINOXALIN-2(1H)ONES FROM 3,4-DIHYDROQUINOXAL IN-2(1H) ONES

摘要

An improved process for the preparation of quinoxalin-2 (IH) one of the formula Ishown in the drawings accompanying the provisional specification wherein.(a) R3, R5, R6, R7 and R8 represents hydrogen or(b) R3, R5, R7 and R8 each represents hydrogen when R6 represents CO2H or(c) R3, R5, R6 and R8 each represents hydrogen when R7 represents chlorine of(d) R5, R6, R7 and R8 each represents hydrogen when R3 represents a phenyl or(e) R5, R6, and R8 each represents hydrogen when R-represents bromine and R3 represents CH3 or(f) R5, R7 and R8 each represents hydrogen when R6 represents bromine and R3 represents CH3 or(g) R5, R6, R7 and R8 each represents hydrogen when R3 represents CO2Hwhich comprises oxidizing a corresponding 3, 4-dihydroquinoxalin-2 (1H) one of the formula IIshown in the drawings accompanying the provisional specification wherein R3, R5, R6, R7 and R8 are as defined above in an alkaline medium in the presence of molecular, oxygen at a temperature between 25 degree to 80 degree C, and recovering the product from the resulting solution in a known manner.