New Fused as‐Triazines with Bridgehead Nitrogen Synthesis and Reactivity

Abstract

Two synthetic pathways have been elaborated for,the synthesis of py~ido[l,2-b]-as-triazinium salts and were also extended to the linearly fused as-triazino [2,3-b]isoquinolin1um and the angularly fused as-triazino[3,2-a]isoquinolinium systems. The ring closures were found to proceed in regioselective manner which was rationalized by assumption of the different charge distribution in acidic and basic conditions. Preparative route has also been worked out for the synthesis of pyrido[2,l-fl-as-triazinium salts and its differently (linearly and an ularly) fused benzologues. The new heteroaromatic ring systems easily formed covalent hydrate salts u n g r acidic conditions and pseudo bases with nucleophiles under basic conditions.

1,2,4-Triazine Chemistry Part IV: Synthesis and Chemical Behavior of 3-Functionalized 5,6-Diphenyl-1,2,4-triazines towards Some Nucleophilic and Electrophilic Reagents

“…Enamines, ketene‐ N , N ‐acetals, O , O ‐acetals, and N , S ‐acetals and other electron‐rich alkenes reacted with 1,2,4‐triazines as dienophiles to cause transformation of the ring via inverse electron‐demand Diels–Alder cycloaddition reactions . Thus, the reaction of 3,5,6‐triphenyl‐1,2,4‐triazine ( 10 ) with the enamine 13 gave the adduct 14 via the addition reactions to C ‐5 of 1,2,4‐triazine ring (Scheme ) .…”

One-Pot Synthesis of Linearly Fused N-Heterocyles from Their Angular Analogues and Studies of Their Redox and Electrochromic Properties

“…The chemical transformations concerning us here are depicted in Scheme . Literature survey has revealed that linearly fused tricyclic triazinium salts are usually prepared from α-diaminoisoquinolinium salts and α-dioxo compounds.…”