Photoalkylation of s-Triazolopyridazine with Alcohols and Glycols

Article abstract of DOI:10.1021/jo01300a011

s-Triazolo<4,3-b>pyridazine (1) was irradiated in 1-butanol to yield 8- and 7-(1'-hydroxybutyl)-7,8-dihydro-s-triazolo<4,3-b>pyridazines (5 and 6) which were isolated and characterized.When this mixture was heated to 260 deg C, 8- and 7-n-butyl-s-triazolo<4,3-b>pyridazines (2a and 3a) were isolated.Similar 8- and 7-alkylated compounds were prepared from the photoalkylation of 1 with 1-octanol (2b and 3b), cyclohexanol (2c and 3c), benzyl alcohol (2d and 3d), and 1,4-butanediol (2e and 3e). 7,8-Dihydro-s-triazolo<4,3-b>pyridazine (4) was also isolated from the reaction mixture of the irradiation of 1 with cyclohexanol and with benzyl alcohol. 8-n-Butyl-7-methyl- and 7,8-di-n-butyl-s-triazolo<4,3-b>pyridazines (7 and 8) have also been prepared.When 2e or a mixture of 2e and 3e was irradiated for 4 h and the reaction mixture heated, 7,8,9,10-tetrahydro-s-triazolo<3,4-a>phthalazine (9) was the only product isolated.Compound 9 was also prepared by an independent synthesis.