反应详情

135 ml of n-butyllithium (1.6M in n-hexane) are added dropwise at 0° C. under argon to a suspension of 73.9 g (0.215 mol) of methoxymethyltriphenylphosphonium chloride in 500 ml of anhydrous tetrahydrofuran in such a manner that the temperature does not exceed 5° C. After stirring at 0° C. for 30 minutes a solution of 50 g (0.178 mol) of 2-(2,4-dichlorophenyl)-1-(3-pyridyl)-1-propanone in 100 ml of dry tetrahydrofuran is added dropwise at -75° C. within 30 minutes. The mixture is stirred at this temperature for 3 hours and 100 ml of water are then added dropwise at 0° C. The tetrahydrofuran is distilled off under reduced pressure and the residue is extracted with ethyl acetate. After distilling off the ethyl acetate the oily residue is chromatographed on silica gel with dichloromethane/ethyl acetate (95:5 vol%) as the eluent. There is thus obtained with the 1st fraction (E)- 3-(2,4-dichloro-α-methoxy methylene-β-methylphenethyl)-pyridine as beige crystals, m.p. 67-68° C., and with the 2nd fraction (Z)-3-(2,4-dichloro-α-methoxymethylene-β-methylphenethyl)-pyri dine as a yellowish oil in the ratio of about 1:1 in a total amount of 44.4 g.

1. customdoes not exceed 5° C
2. additionis added dropwise at -75° C. within 30 minutes
3. distillationThe tetrahydrofuran is distilled off under reduced pressure
4. extractionthe residue is extracted with ethyl acetate
5. distillationAfter distilling off the ethyl acetate the oily residue
6. customis chromatographed on silica gel with dichloromethane/ethyl acetate (95:5 vol%) as the eluent