Synthesis 2014; 46(07): 909-916
DOI: 10.1055/s-0033-1338593
paper
© Georg Thieme Verlag Stuttgart · New York

Cycloaddition of Styrenes as Phenylacetylene Substitutes on 2H-Pyran-2-ones and the Consequent Metal-Free Dehydrogenation: Case Study of Boscalid Derivatives­

Amadej Juranovič
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia   Fax: +386(1)2419220   Email: marijan.kocevar@fkkt.uni-lj.si
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Krištof Kranjc
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia   Fax: +386(1)2419220   Email: marijan.kocevar@fkkt.uni-lj.si
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Slovenko Polanc
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia   Fax: +386(1)2419220   Email: marijan.kocevar@fkkt.uni-lj.si
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Marijan Kočevar*
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia   Fax: +386(1)2419220   Email: marijan.kocevar@fkkt.uni-lj.si
› Author Affiliations
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Publication History

Received: 30 November 2013

Accepted after revision: 10 January 2014

Publication Date:
07 February 2014 (online)


Dedicated to Professor Bojan Verček, University of Ljubljana, Slovenia, on the occasion of his 65th birthday

Abstract

A novel use of styrenes as synthetic equivalents of phenylacetylenes is presented. To show its applicability, the method was tested for the preparation of a set of derivatives of boscalid, a commercially important fungicide. The strategy incorporates the Diels–Alder reaction of 3-acylamino-2H-pyran-2-ones with styrenes, followed by an efficient dehydrogenation step. The latter can be achieved either by the use of chloranil as the oxidant (under microwave irradiation) or by the application of activated charcoal Darco KB acting as a dehydrogenation catalyst (conventional heating).

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