ChemInform Abstract: 5-Chloropyrazole-4-carbaldehydes as Synthons for Intramolecular 1,3- Dipolar Cycloadditions.
Abstract
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ChemInform Abstract
The title compound (I) is transformed into tricyclic heterocycles (IV), (VI), (IX) or (XI) in a short and attractive reaction sequence consisting of substitution of the chlorine atom, conversion of the aldehyde function into 1,3-dipoles and final intramolecular cycloaddition. Simultaneous Claisen rearrangement of the 5-allyloxy analogue of (III) limits its use for intramolecular 1,3-dipolar cycloaddition. Instead the homologous derivative (XII) can be used.
