Synthesis 2016; 48(23): 4253-4259
DOI: 10.1055/s-0035-1560565
paper
© Georg Thieme Verlag Stuttgart · New York

Type 2 Ring-Opening Reactions of Cyclopropanated 7-Oxabenzonorbornadienes with Carboxylic Acid Nucleophiles

Emily Carlson
Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1, Canada   Email: wtam@uoguelph.ca
,
Daniel Hong
Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1, Canada   Email: wtam@uoguelph.ca
,
William Tam*
Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1, Canada   Email: wtam@uoguelph.ca
› Author Affiliations
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Publication History

Received: 20 June 2016

Accepted after revision: 20 July 2016

Publication Date:
24 August 2016 (online)


Abstract

Ring-opening reactions of strained heterocyclic compounds provide efficient routes to various organic frameworks. In this work, the ability of carboxylic acid nucleophiles to promote ring-opening of cyclopropanated 7-oxabenzonorbornadienes was investigated. Reactions proceeded smoothly to yield 2-naphthylmethyl esters in moderate yields, and optimal conditions were found with the use of 10 mol% p-toluenesulfonic acid monohydrate in dichloroethane heated to 90 °C. The amount of nucleophile could be decreased from a large excess to 8 equivalents without diminishing the yield. When varying the structure of the acid catalyst or carboxylic acid nucleophile, reaction rates showed a marked dependence on acidity of these species. Ring-opening was well tolerated by functionalized substrates, with substitution on the bridgehead or aromatic portions of the molecule. The present work is the second account of this type of reaction, and provides a new route to 2-naphthylmethyl esters. The transformations observed in this work should be useful in predicting the reactivity of similar fused-ring systems.

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