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Intramolekulare 1,3‐dipolare Cycloadditionen von Diarylnitriliminen aus 2,5‐Diaryltetrazolen
Author(s) -
Meier Hansruedi,
Heimgartner Heinz
Publication year - 1985
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19850680524
Subject(s) - chemistry , nitrile , intramolecular force , cycloaddition , regioselectivity , imine , yield (engineering) , medicinal chemistry , thermal decomposition , photodissociation , stereochemistry , organic chemistry , catalysis , materials science , metallurgy
Intramolecular 1,3‐Dipolar Cycloadditions of Diaryl‐nitrile‐imines Generated from 2,5‐Diaryl‐tetrazoles Alkenyl‐substituted diaryl‐nitrile‐imines – generated by photolysis or thermolysis of alkenyl‐substituted 2,5‐diaryl‐tetrazoles ‐ undergo a regioselective intramolecular [2 + 3] cycloaddition to yield new heterocyclic compounds, e. g. fused 2‐pyrazolines. With alkinyl derivatives, the corresponding pyrazoles have been formed. UV evidence is given for the intermediate nitrile‐imine at − 190°. The latter can be trapped using an excess of carboxylic acid (UV evidence for a new intermediate at − 120°). In this case, the corresponding rearranged addition product N ′‐acyl‐ N ′‐aryl‐benzohydrazide is isolated in good yield.