Hexane → HCID 57294432、化合物

To a solution of (R)-2,5-dihydro-3,6-dimethoxy-2-isopropyl-pyrazine (5.53 g, 30 mmol) in anhydrous THF (80 ml) a 1.6M solution of n-BuLi in hexane (10.85 ml, 17.36 mmol) was added at -78° C. After 30 minutes a solution of bromomethyl methyl ether (4.5 g, 36 mmol) in THF (20 ml) was added dropwise. The reaction mixture was allowed to come to 20° C. overnight and was quenched by addition of 1M phosphate buffer (pH 7, 80 ml). The turbid mixture was stirred for 10 minutes, diluted with water (250 ml) and diethyl ether (180 ml). The layers were separated and the aqueous phase extracted with diethyl ether (2×150 ml). The combined organic layer was dried (Na2SO4), concentrated and purified by flash chromatography (silica gel; hexane:diethyl ether 5:1) to yield 5.61 g. To remove final impurities of the other diastereomer the material was crystallized from acetonitrile at -30° C. and the cold precipitate redissolved in CH2Cl2, dried (Na2SO4) and concentrated.