Pyrazolo pyrrolizines

Zum gleichen Anellierungstyp gehoren die Pyrazolo[4,3-b]pyrrolizine, die aus 4-Carboxy-5-pyrrolo-1H-pyrazol-Derivaten durch intramolekulare Acylierung zuganglich sind2154 ... 

Intramolecular nitrilimine cycloadditions gave new pyrazolo[4,3-c]pyrrolizines 50 <04H(63)1423>. The syntheses of 5-substituted ethyl 3-oxo-2/7-pyrazolo[4,3-c]pyridlne-7-carboxylates 51 <04H(63)609> and 5//-pyrazolo[4,3-c]quinolines 52 <04H(63)1883> have been described. Ring-closure reactions of 3-arylhydrazonoalkyl-quinolin-2-ones gave rise to 1-aryl-pyrazolo[4,3-c]quinolin-2-ones <04JHC681>. 

The synthesis of 1-phenyl-l//,4//-pyrazolo[4,3-Z)]pyrrohzine (136) and 2-phenyl-2//,4//-pyrazolo[4,3-Z)]pyrrolizine (143) has been accomplished via the respective keto derivatives (135) and (142) starting with l-phenyl-5-(l//-pyrrol-l-yl)-l//-pyrazole-4-carboxylic acid (133) and ethyl-3-amino-1-phenyl-l//-pyrazole-4-carboxylate (137) respectively (Schemes 11 and 12) <90JHC1805>. 

Molteni G (2004) Synthesis of the new pyrazolo[4,3-c]pyrrolizine skeleton via intramolecular nitrilimine cycloaddition. Heterocycles 63 1423-1428 52. Padwa A, Hertzog DL et al (1994) Studies on the intramolecular cycloaddition reaction of mesoionics derived from the rhodium(II)-catalyzed cyclization of diazoimides. J Org Chem 59 1418-1427... 

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