QUINOL N-ACYL AND QUINOL ETHER IMINES VIA ANODIC-OXIDATION OF PARASUBSTITUTED ANILIDE DERIVATIVES

Anodic oxidation of N-benzoyl-4-methylaniline in 5 % aqueous methanol in the presence of sodium bicarbonate affords two major products: 4-me thoxy-4-methylbenzoquinol N-benzoylimine, 8a, and a dimer, nzoyl-N-(4- methylphenyl)amino]-4-methylbenzoquinol N-benzoylimine, 9. The ratio o f these two products was temperature dependent, and conditions were de veloped for preparing 8a and 9 in good yield. Using the conditions dev eloped for 8a, the anodic methoxylation of N-benzoyl and acetyl deriva tives of 4-ethyl- and 4-sec-butyl-4-phenylaniline and 2-aminofluorene derivatives was performed. The yields of the N-benzoyl derivatives of the 4-methoxy-4-substituted-benzoquinol imines were 46-80%, while the N-acetyl derivatives gave lower yields. When the anodic oxidation was performed using 30% water/acetonitrile or 10 % water/tetrahydrofuran, the 4-alkylbenzoquinol N-benzoylimine derivatives were obtained. The y ields of these anodic hydroxylation reactions were lower than those of the corresponding methoxylations for all systems studied. In addition , the 4-alkylbenzoquinol N-benzoylimine derivatives were much more lab ile. Two methods were developed for conversion of the 4-methoxy-4-subs tituted-benzoquinol N-acylimines to the 4-methoxy-4-substituted-benzoq uinol N-alkylimines. Finally, the especially labile 4-hydroxy-4-phenyl benzoquinol N-acetylimine was prepared for the first time from the rea dily available N-benzoyl derivative.