SCHEDULED MAINTENANCE
8π-Six-atom rings: 1,3,4,5-oxa- and -thia-triazines and 1,2,3,5-tetrazines from an extended tandem reaction: reactions of 1,2,3-triazolium-1-imides with (E)-cinnamaldehyde, methyl cyanodithioformate, and aryl-N-sulphinylamines: new tetrahydro-oxazolo[4,5-d]-1,2,3-triazoliumides and triazaspiro-[4.4]nonanes. Azolium 1,3-dipoles. Part 4
Abstract
The reactions of substituted 1,2,3-triazolium-1-imides with (E)-cinnamaldehyde, methyl Cyanodithioformate, and aryl-N-sulphinylamines gave rise to substituted 1,3,4,5-oxatrizines, 1,3,4,5-thiatriazines, and 1,2,3,5-tetrazines, respectively. Each of these is an 87π-six-atom ring. The routes were similar in each case and involved an extended tandem sequence of cycloaddition, rearrangement, fragmentation, and ring expansion. New oxazolo[4,5-d]-1,2,3-triazoles which were formed along the route to the 1,3,4,5-oxatriazines were isolated as stable compounds. The structures and reactivity of the 8π-six-atom rings are discussed. X-Ray crystal structures are reported for 4-(p-bromophenyl)-2,6-diphenyl-4H-1,3,4,5-oxatriazine (6b); 2,4,6-triphenyl-4H-1,3,4,5-thiatriazine (11a); 5-(p-bromophenyl)-2,5-dihydro-2,4,6-triphenyl-1,2,3,5-tetrazine (17b); 2,6-bis(p-bromophenyl)-3a,5,6,6a-tetrahydro-3a,6a-diphenyl-5exo-styryloxazolo[4,5-d]-1,2,3-tri-azol-2-ium-1-ide (4b); and 4-[(5′-methylisoxazol-3′-yl)imino]-2-(p-nitrophenyl)-1,2,3-triazaspiro[4.4]non-1-en-2-ium-3-ide (19b).
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