Synthesis of Chiral 18-Crown-6 Derivatives and Dibenzocrown Ethers Incorporating trans-Tetrahydrofuran-2,5-diylbis(methylene) Units of Known Absolute Configuration

Abstract
By using (−)-trans-2,5-bis(hydroxymethyl)tetrahydrofuran (1) of known absolute configuration as a chiral diethylene glycol unit, 18-crown-6 derivatives 8, 9, 12, and dibenzocrown ethers 14, 15 containing trans-tetrahydrofuran-2,5-diylbis(methylene) unit were prepared in enantiomerically pure forms. Their abilities to extract alkali metal picrates were investigated.