NEW ROUTE TO 2-CYANOBENZIMIDAZOLES

N-Monosubstituted 1,2-diaminobenzenes 4 (R = Me, Ph, PhCH2, and 3,4-Me 2Cb6H3CH2) react with 4,5-dichloro-1,2,3-dithiazolium chloride 1 in di chloromethane at room temperature to give the corresponding 2-cyanoben zimidazoles 6. If pyridine is added at the beginning of the reaction, the intermediate imino-1,2,3-dithiazoles 5 can be isolated. Upon therm olysis. most of the imines 5 give the 2-cyanobenzimidazoles 6 in fair to good yields 1,2-Diaminobenzene can be converted in high yield into the mono-imine 5i or the bis-imine 12, R = H; thermolysis of 5i gives 2-cyanobenzimidazole in high yield. Conversion of 5 into 6 involves th e loss of both sulfur atoms and with the N-phenylimino derivative 5b s inglet diatomic sulfur, S-2, has been intercepted with norbornene and with 2.3-diphenylbutadiene to give the expected cycloadducts 7 and 8. (C) 1998 Elsevier Science Ltd. All rights reserved.