Synlett 2011(11): 1523-1526  
DOI: 10.1055/s-0030-1260776
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

2,6-Disubstituted Tetrahydropyrans by Domino Meyer-Schuster Rearrangement-Hetero-Michael Addition of 6-Alkyne-1,5-diols

Max Wohland, Martin E. Maier*
Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen
Fax: +49(7071)295137; e-Mail: martin.e.maier@uni-tuebingen.de;
Further Information

Publication History

Received 9 February 2011
Publication Date:
10 June 2011 (online)

Abstract

Starting from pentanediol various oct-6-yne-1,5-diols were prepared. In the presence of catalytic amounts of an Au(I) or Pt(II) catalyst transformation to cis-2,6-tetrahydropyrans was observed. It is assumed that this novel domino sequence proceeds via an initial Meyer-Schuster rearrangement of the propargylic alcohol yielding a hydroxyenone that undergoes an intramolecular oxa-Michael addition through a chairlike transition state to the tetra­hydropyran system.

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We found the use of AgO2CCF3 (AgTFA) for the generation of the active Au(I) catalyst to be more convenient over AgSF6 because of its greater stability. In case of substrate 20a, it could be shown that the reaction to 21a works with comparable yield with a catalyst generated from Ph3PAuCl and AgSF6.