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  • Iodine-catalyzed synthesis of five-membered cyclic ethers from 1,3-diols under solvent-free conditions.

Iodine-catalyzed synthesis of five-membered cyclic ethers from 1,3-diols under solvent-free conditions.

Journal of oleo science (2009-07-09)
Yoshio Kasashima, Atsushi Uzawa, Tadasuke Nishida, Takashi Mino, Masami Sakamoto, Tsutomu Fujita
ABSTRACT

Intramolecular etherification of 1,3-diols was investigated using iodine as a catalyst under solvent-free conditions. The reaction proceeded to completion in a heterogeneous system. Five-membered cyclic ethers were obtained by intramolecular cyclization of 1,3-diols with dehydration. A propella ether (11-oxatricyclo[4.4.3.0(1,6)]tridecane) was conveniently synthesized from a 1,3-diol (6-(2-hydroxyethyl)spiro[4.5]decan-6-ol) in 86% yield with carbon skeleton rearrangement under the following conditions: a temperature of 60 degrees C, a molar ratio of 1,3-diol:iodine = 1:0.2, and a time period of 3 h. Bicyclic ethers were also obtained from the corresponding 1,3-diols, but spiro ethers were obtained in lower yield. Terpenic cyclic ethers were efficiently synthesized from the corresponding 1,3-diols, derived from (+)-camphor and (-)-fenchone. In the case of etherification with a mechanism of carbon skeleton rearrangement, the yield of the solvent-free reaction was as high as that of the corresponding reaction in solution. Etherification reactions with carbon skeleton rearrangement proceeded more smoothly than those with hydride shift.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
(+)-Fenchone, purum, ≥98.0% (sum of enantiomers, GC)
Supelco
(+)-Fenchone, analytical standard
Sigma-Aldrich
L-Fenchone, ≥98%
Sigma-Aldrich
(1R)-(−)-Fenchone, ≥98%