Synlett 2005(20): 3142-3144  
DOI: 10.1055/s-2005-921898
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Bench-Stable Organic Salt for the Benzylation of Alcohols

Kevin W. C. Poon, Sarah E. House, Gregory B. Dudley*
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA
Fax: +1(850)6448281; e-Mail: [email protected];
Further Information

Publication History

Received 21 September 2005
Publication Date:
04 November 2005 (online)

Abstract

2-Benzyloxy-1-methylpyridinium triflate (Bn-OPT) effects the benzylation of alcohols in the absence of acidic or basic promoters. Solutions of Bn-OPT and primary, secondary, or tertiary alcohols give rise to the corresponding benzyl ethers upon mild heating. Acid scavengers are generally included in the reaction mixture. Bn-OPT is crystalline and bench-stable.

    References

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    (c) We prepared 1 by the following procedure, which is a modification of that reported in ref. 7a: A toluene solution of benzyl alcohol (0.5 M, 1.0 equiv), 2-chloro-pyridine (1.2 equiv), KOH (3.2 equiv, powdered with a mortar and pestle), and 18-crown-6 (0.05 equiv) was heated at reflux for 1 h with azeotropic removal of water. Routine aqueous workup and purification on silica gel afforded 1 in 96% yield.

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2

TfOH is generally required, whereas milder acids will promote the formation of p-methoxybenzyl ethers; see ref. 1.

3

Scattered literature reports provided the foundation for this work. In particular, alkoxypyridinium bromides decompose to pyridones and alkyl bromides via nucleophilic attack of the bromide ion (ref. 4), whereas alkoxypyridinium sulfonates are isolable (ref. 5). Note that Mukaiyama’s reagent (ref. 6) has been employed to convert alcohols into thioesters and azides.