(2,4,6-Triisopropylphenyl)seleniumBromide

Abstract

[130248-05-4] C15H23BrSe (MW 362.2) InChI = 1S/C15H23BrSe/c1-9(2)12-7-13(10(3)4)15(17-16)14(8-12)11(5)6/h7-11H,1-6H3 InChIKey = KJQSKARBIIMOGJ-UHFFFAOYSA-N (reagent used for the stereoselective ring closure of homoallylic alcohols to generate substituted tetrahydrofurans1) Alternate Name: TIPPSe-Br. Solubility: soluble in organic solvents. Form Supplied in: generated in situ. Preparative Methods: the reagent is generated in situ from di-(2,4,6-triisopropylphenyl)diselenide 1. Preparation of 1 (eq 1) is performed by lithium-halogen exchange of bromo-2,4,6-triisopropylbenzene 2 in THF with 2.3 equiv of t-BuLi added at −78 °C and then at 0 °C for 30 min. Selenium powder (1.06 equiv) is added in one portion turning the yellow solution reddish orange. The reaction is stirred for 15 min at 0 °C, then for 30 min at room temperature. The mixture is quenched by the addition of 1 M HCl and then extracted with ether. The organic layer is dried over anhydrous Na2SO4. (1) (2,4,6-Triisopropylphenyl)selenium Bromide (TIPPSe-Br) is generated upon treatment of the diselenide 1 with 1.0 equiv of bromine in DCM at −78 °C for 30 min (eq 2). (2) Purification: the drying agent was removed by filtration, the solution concentrated in vacuo and the residue purified by flash chromatography on silica gel (100% petroleum ether). Concentration in vacuo produced orange crystals. Recrystallization from ethanol led to yellow crystals in 86% yield. Mp 101–103 °C. Handling, Storage, and Precautions: store in a closed container. No noticeable degradation after 12 months at room temperature.