Synlett 2010(19): 2879-2882  
DOI: 10.1055/s-0030-1259038
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Gold-Catalyzed Stereoselective Synthesis of Di- or Trisubstituted Olefins Possessing a 1,4-Diene Framework via Intramolecular Allylation of Alkynes

Yoshikazu Horino*, Yuichi Nakashima, Ken Hashimoto, Shigeyasu Kuroda*
Department of Applied Chemistry, Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, 930-8555, Japan
Fax: +81(76)4456819; e-Mail: horino@eng.u-toyama.ac.jp; e-Mail: kuro@eng.u-toyama.ac.jp;
Further Information

Publication History

Received 12 July 2010
Publication Date:
10 November 2010 (online)

Abstract

The cationic gold(I)-catalyzed reaction of 1-alkynyl-2-allylsilylbenzenes with water results in intramolecular allylation of the alkynes via 7-exo-dig cyclization to give 1,4-dienes in good yield with excellent stereoselectivities.

9

Use of phenol as a nucleophile in place of water gave a complex mixture.

14

AgNTf2, PtCl2, (PPh3)2PtCl2/2AgNTf2, and Sc(OTf)3 did not show any catalytic activities. Furthermore, background reaction mediated by Tf2NH did not proceed, either.

18

For details, see Supporting Information.

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Another interesting alternative mechanism for the formation of 2, as suggested by one referee, involves initial formation of 3-allyl-1-silaindenes and their subsequent hydrolysis. Indeed, we have observed the formation of 2 from isolated 3-allyl-1-silaindenes under our reaction conditions. However, we were unable to detect such intermediates when monitoring the reaction of 1 by ¹H NMR spectroscopy (see Supporting Information for further details). Nevertheless, we would like to thank the referee for this suggestion.