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Sodium borohydride (2.2 g) was added in four portions, over 10 minutes, to an ice-cooled solution of 4-(3,4-dichlorophenyl)-4-formylbut-1-ene (13 g) (see Preparation 21) in ethanol (100 ml). The mixture was stirred for a further 30 minutes before removing the solvent under reduced pressure to give a residue. This was suspended in water (50 ml), cooled to 0° C. and the mixture acidified (pH<6) with 2N aqueous hydrochloric acid solution. The mixture was extracted three times with dichloromethane, the organic phases combined and the solvent removed under reduced pressure. Dichloromethane (200 ml) was then added, the mixture stirred and filtered and the solvent removed from the filtrate under reduced pressure to give an oil. This was chromatographed on silica gel eluting with dichloromethane to give 4-(3,4-dichlorophenyl)-5-hydroxypent-1-ene (7 g) as a orange oil.

1. custombefore removing the solvent under reduced pressure
2. customto give a residue
3. extractionThe mixture was extracted three times with dichloromethane
4. customthe solvent removed under reduced pressure
5. additionDichloromethane (200 ml) was then added
6. stirringthe mixture stirred
7. filtrationfiltered
8. customthe solvent removed from the filtrate under reduced pressure
9. customto give an oil
10. customThis was chromatographed on silica gel eluting with dichloromethane