104739-25-5Relevant articles and documents
Cycloaddition Reactions of Cyclic Ketene-N,S-Acetals
Marcelis, Antonius T. M.,Plas, Henk C. van der
, p. 545 - 548 (2007/10/02)
Reaction of 3,6-diphenyl-, 3,6-bis(2-pyridyl)- and the unsubstituted 1,2,4,5-tetrazine with 4,5-dihydro-1-methyl-2-(methylthio)pyrrole (2) and 1-methyl-2-(methylthio)-4,5,6,7-tetrahydroazepine (3) gives 4,7-di-R-2,3-dihydro-1-methylpyrrolopyridazine (4, R = phenyl, 2-pyridyl, hydrogen) and 6,9-di-R-1-methyl-2,3,4,5-tetrahydropyridazinoazepine (5), R = phenyl, 2-pyridyl, hydrogen), respectively, in reasonable to good yields.The compounds 4 (R = phenyl, hydrogen) are converted into their corresponding 1-methylpyrrolo-pyridazines 6 by reaction with potassium permanganate in butanone.Reaction of 3-phenyl-1,2,4,5-tetrazine with 2 and 3 leads to the exclusive formation of the 7-phenyl isomer 4d and 9-phenyl isomes 5d, respectively, indicating that the cycloaddition is regiospecific.The mechanism is discussed.