The general procedure for the synthesis of (R)-3,3'-dimethyl-[1,1'-binaphthyl]-2,2'-diols from (R)-2,2'-bis(methoxymethoxy)-1,1'-binaphthyl and dimethyl sulfate was as follows: firstly, 18.3 g of sodium hydride was mixed with 50 g (0.175 mol) of (R)- 2,2'-dihydroxy-1,1'-binaphthyl suspended in 1.0 L of anhydrous tetrahydrofuran (THF) under nitrogen protection and stirred for 1 hour. Subsequently, 116 g of chloromethyl methyl ether was added to the reaction system and stirring was continued for about 12 hours. Upon completion of the reaction, the reaction mixture was filtered through a diatomaceous earth pad. The filtrate was subsequently mixed with 500 ml of water and 1 L of dichloromethane for liquid-liquid extraction. After separation of the aqueous layer, the aqueous layer was subjected to a secondary extraction with dichloromethane. The organic layers were combined, washed with saturated aqueous potassium bicarbonate, dried and filtered through a short column of alumina. The filtrate was evaporated until crystals precipitated and the crude product was purified by silica gel column chromatography (eluent: dichloromethane/hexanes) to give about 53.5 g (63% yield) of (R)-2,2'-bis(methoxymethoxy)-1,1'-binaphthalene with a melting point of 93-94°C. The product was purified by silica gel column chromatography.
Next, 171 ml of 1.6 M butyl lithium hexane solution was added dropwise to 41 g of the above bisacetal dissolved in 1 L of tetrahydrofuran and stirred at 0°C for 45 min under nitrogen protection. Subsequently, the reaction system was warmed to 25°C, 25.8 ml of dimethyl sulfate was added and stirring was continued for 12 hours. At the end of the reaction, about 30 ml of saturated aqueous sodium carbonate solution was added and the solvent was evaporated at 50°C under reduced pressure. The residue was dissolved with 300 ml of dichloromethane and washed twice with water. Subsequently, 300 ml of dichloromethane, 300 ml of methanol and 25 ml of concentrated hydrochloric acid were added to the organic phase and the solvent was evaporated after stirring for 3 hours. The resulting yellow product was recrystallized by dichloromethane-hexane and purified by silica gel column chromatography (eluent: dichloromethane/hexane=1:1) to give 29.5 g (86% yield) of (R)-3,3'-dimethyl-[1,1'-binaphthyl]-2,2'-diol with a melting point of 204-206°C. 1H NMR (CDCl3) δ: 2.2 (s, 6H) , 7.1 (d, 2H), 7.3 (m, 2H), 7.4 (m, 2H), 7.8 (m, 4H).
