Fluorous Tetrahydropyranyl Ether (THP, 2-Benzenesulfinyl-3-heptadecafluorooctyltetrahydropyran)

Abstract

[234084-47-0] C19H13F17O2S (MW 628.34) InChI = 1S/C19H13F17O2S/c20-12(21,10-7-4-8-38-11(10)39(37)9-5-2-1-3-6-9)13(22,23)14(24,25)15(26,27)16(28,29)17(30,31)18(32,33)19(34,35)36/h1-3,5-6,10-11H,4,7-8H2/t10-,11-,39?/m1/s1 InChIKey = QGNZWIUTMUJQID-AWQWYQQTSA-N (reagent used to protect hydroxyl groups; protected substrates are rendered fluorous soluble and can be purified by fluorous liquid-liquid or solid-phase extraction techniques; after cleavage fluorous label can be recycled) Physical Data: mp 66–69 °C. Solubility: soluble in tetrahydrofuran, dichloromethane, acetonitrile; insoluble in H2O. Analysis of Reagent Purity: 1H and 13C NMR, IR, elemental analysis. Preparative Methods: the fluorous THP is prepared by a three-step sequence (eq 1)1 initially involving treatment of a methanolic solution of perfluoro-n-octyl iodide, triethylamine, and [CpFe(CO)2]2 with 3,4-Dihydro-2H-pyran to give a methoxy-substituted fluorous THP group. This methyl acetal is then exchanged with thiophenol to give a phenylthioacetal, which is subsequently oxidized with meta-chloroperbenzoic acid to give the desired sulfoxide. The minor, less reactive trans-diastereomer is removed at this stage by flash column chromatography on silica. The diastereomers may also be separated prior to oxidation to the sulfoxides, although with more difficulty since the RF difference is much smaller between the diastereomeric thioacetals. (1) Handling, Storage, and Precautions: reagent is best stored under a nitrogen atmosphere in a dry environment.