1.2.4- Triazolo isoquinoline, 3-phenyl

Reaction of 1-chloroisoquinoline with 5-phenyltetrazole gave 3-phenyl[l,2,4]triazolo[3,4-n]isoquinoline (428). It has been suggested that the initial 2-tetrazolylisoquinoline (425) underwent ring opening to (426) which readily lost N2 giving (427). This nitrilimine is a 1,5-dipole, and on cyclization the [l,2,4]triazolo[3,4-n]isoquino-line (428) is formed (70CB1918). 

The diazopyrazole (93) with various phosphorus ylides afforded 3/7-pyrazolo[5,l-c]-1,2,4-triazoles (94) by elimination of triphenylphosphine (79TL1567). Reaction of 1-chloroisoquinoline with 5-phenyltetrazole gives 3-phenyl-1,2,4-triazolo[3,4-a]isoquinoline (96) via intermediate (95) (70CB1918) (cf conversion 86 — 87). 

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