Bicyclo[2.2.2]octa-2,5-diene, 2,5-Diphenyl-, (1R,4R) and Bicyclo[2.2.2]octa-2,5-diene, 2,5-Diphenyl-, (1S,4S)

Abstract

(1R,4R)-isomer [796966-15-9] InChI = 1S/C20H18/c1-3-7-15(8-4-1)19-13-18-12-11-17(19)14-20(18)16-9-5-2-6-10-16/h1-10,13-14,17-18H,11-12H2/t17-,18-/m1/s1 InChIKey = BDYBOFJAEBJDMI-QZTJIDSGSA-N (1S,4S)-isomer [850409-83-5] C20H18 (MW 258.36) InChI = 1S/C20H18/c1-3-7-15(8-4-1)19-13-18-12-11-17(19)14-20(18)16-9-5-2-6-10-16/h1-10,13-14,17-18H,11-12H2/t17-,18-/m0/s1 InChIKey = BDYBOFJAEBJDMI-ROUUACIJSA-N (reagent used as a chiral ligand for rhodium-catalyzed asymmetric addition of organometallic reagents to unsaturated bonds) Physical Data: mp 69–70 °C; –30 ° (c 0.72, CHCl3, (1R,4R)-isomer). Solubility: sol in many organic solvents such as THF, toluene, and dichloromethane. Form Supplied in: white solid. Analysis of Reagent Purity: 1H NMR. Preparative Method: this reagent is prepared in a racemic form in two steps from (±)-bicyclo[2.2.2]octa-2,5-dione: (1) treat it with lithium diisopropylamide, and then with N-(2-pyridyl)trifluoromethanesulfonimide to give (±)-2,5-bis(trifluoromethanesulfonyloxy)bicyclo[2.2.2]octa-2,5-diene; (2) treat this compound with phenylmagnesium bromide in the presence of PdCl2(dppf) (1 mol %) in refluxing diethyl ether for 8 h. The separation of the enantiomers is achieved by preparative chiral HPLC using a Chiralcel OJ column with hexane/2-propanol to give enantiopure (1R,4R)- and (1S,4S)-isomers.1 Purification: chromatography on silica gel with hexane/benzene (10/1). Handling, Storage, and Precautions: this reagent is an air-stable solid and can be stored and handled at room temperature.