Synthesis of Spirobicyclic Pyrazoles by Intramolecular Dipolar Cycloadditions/[1s, 5s] Sigmatropic Rearrangements

Synthesis of Spirobicyclic Pyrazoles by Intramolecular Dipolar Cycloadditions/[1s, 5s] Sigmatropic Rearrangements

The formation of fused pyrazoles via intramolecular 1,3-dipolar cycloadditions of diazo intermediates with pendant alkynes is described. A subsequent thermal [1s, 5s] sigmatropic shift of these pyrazole systems resulted in a ring contraction, forming spirocyclic pyrazoles. The limitations of this re...

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Bibliographic Details
Published in:Organic letters Vol. 21; no. 18; pp. 7209 - 7212
Main Authors: Dimirjian, Christine A, Castiñeira Reis, Marta, Balmond, Edward I, Turman, Nolan C, Rodriguez, Elys P, Di Maso, Michael J, Fettinger, James C, Tantillo, Dean J, Shaw, Jared T
Format: Journal Article
Language:English
Published: United States American Chemical Society 20-09-2019
Online Access:Get full text
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Summary:The formation of fused pyrazoles via intramolecular 1,3-dipolar cycloadditions of diazo intermediates with pendant alkynes is described. A subsequent thermal [1s, 5s] sigmatropic shift of these pyrazole systems resulted in a ring contraction, forming spirocyclic pyrazoles. The limitations of this rearrangement were explored by changing the substituents on the nonmigrating aromatic ring and by using substrates lacking an aromatic linkage to the propargyl group.
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These authors contributed equally.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.9b02124