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Synfacts 2009(8): 0931-0931  
DOI: 10.1055/s-0029-1217502
Polymer-Supported Synthesis
© Georg Thieme Verlag Stuttgart ˙ New York

Preparation of Alkynes and Triazoles Using Modular Flow Reactors

Contributor(s): Yasuhiro Uozumi, Yoichi M. A. Yamada, Toshihiro Watanabe
I. R. Baxendale, S. V. Ley*, A. C. Mansfield, C. D. Smith
University of Cambridge and Pfizer Global R&D Research Centre, Sandwich, UK
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Publication History

Publication Date:
23 July 2009 (online)

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Significance

The Seyferth-Gilbert homologation of aldehydes 2 with 1 (the so-called Ohira-Bestmann reagent) was performed in the continuous flow system A, where the convection flow coil and purification columns were equipped affording the corresponding terminal acetylenes 3 in 84-55% yield (>95% purity, 9 examples). The sequential homologation and cycloaddition were carried out in flow system B [CFC + immobilized copper(I) catalyst (A-21˙CuI) + purification columns] to give the triazoles 6a (69%) and 6b (62%) (>95% purity). Flow system C of sequential oxidation, homologation and cycloaddition was built up to give triazole 9 in 55% yields from 1, 7 and 8.