Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach

(E)-Alkyl ortho-hydroxycinnamates cyclize to coumarins at elevated temperatures of 140–250 °C. We find that the use of tri-n-butylphosphane (20 mol %) as a nucleophilic organocatalyst in MeOH solution allows cyclization to take place under much milder conditions (60–70 °C). Several coumarins were pr...

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Detalles Bibliográficos
Autores principales: Boeck, Florian, Blazejak, Max, Anneser, Markus R, Hintermann, Lukas
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Beilstein-Institut 2012
Materias:
Full Research Paper
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3510995/
https://www.ncbi.nlm.nih.gov/pubmed/23209495
http://dx.doi.org/10.3762/bjoc.8.186
Descripción
Sumario:(E)-Alkyl ortho-hydroxycinnamates cyclize to coumarins at elevated temperatures of 140–250 °C. We find that the use of tri-n-butylphosphane (20 mol %) as a nucleophilic organocatalyst in MeOH solution allows cyclization to take place under much milder conditions (60–70 °C). Several coumarins were prepared, starting from ortho-hydroxyarylaldehydes, by Wittig reaction with Ph(3)P=CHCO(2)Me to (E)-methyl ortho-hydroxycinnamates, followed by the phosphane catalyzed cyclization.

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