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Development of a mild and versatile directed cycloaddition approach to pyridines.

ABSTRACT: The aza-Diels-Alder cycloaddition of 1,2,4-triazines with alkynes offers a rapid and convenient method for the synthesis of highly substituted pyridines, but often requires harsh conditions and long reaction times. The present study offers a solution to these limitations by use of a temporary tether established by a Lewis acid-base complexation of in situ generated alkynylboranes and triazines bearing a Lewis basic donor. The cycloaddition reactions take place within 20?min at 40?°C and provide direct access to a broad range of pyridines with complete and predictable regiocontrol. The carbon?boron bond can be further functionalised by cross-coupling allowing further functionality to be introduced after cycloaddition.

SUBMITTER: Bachollet SP

PROVIDER: S-EPMC4313684 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Development of a mild and versatile directed cycloaddition approach to pyridines.

Bachollet Sylvestre P J T SP Vivat Jérôme F JF Cocker Dean C DC Adams Harry H Harrity Joseph P A JP

Chemistry (Weinheim an der Bergstrasse, Germany) 20140821 40

The aza-Diels-Alder cycloaddition of 1,2,4-triazines with alkynes offers a rapid and convenient method for the synthesis of highly substituted pyridines, but often requires harsh conditions and long reaction times. The present study offers a solution to these limitations by use of a temporary tether established by a Lewis acid-base complexation of in situ generated alkynylboranes and triazines bearing a Lewis basic donor. The cycloaddition reactions take place within 20 min at 40 °C and provide ...[more]

PMID: 25145488

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