C(Cl)(=O)C(Cl)=O.CS(C)=O.[O:11]1[C:16]2[CH:17]=[CH:18][CH:19]=[CH:20][C:15]=2[O:14][CH:13]=[C:12]1[CH2:21][OH:22].C(N(CC)CC)C.Cl>ClCCl>[O:11]1[C:16]2[CH:17]=[CH:18][CH:19]=[CH:20][C:15]=2[O:14][CH:13]=[C:12]1[CH:21]=[O:22]A solution of 1.2 ml (14 mmol) of oxalyl chloride in 30 ml of anhydrous dichloromethane is cooled to −60° C. under an inert atmosphere; 2 ml (28 mmol) of anhydrous dimethyl sulphoxide are then added to the medium. After 5 minutes of stirring, 1.53 g (9.33 mmol) of the alcohol obtained in Step A in 15 ml of dichloromethane are slowly added to the solution. 15 minutes later, 6.5 ml (47 mmol) of triethylamine are added to the medium. After returning to ambient temperature, the solution is acidified with a hydrochloric acid solution (1N); the aqueous phase is then extracted with dichloromethane. The organic phases, dried over magnesium sulphate and then filtered, are concentrated in vacuo. The title aldehyde is obtained pure in the form of a white solid after passage over a silica column (eluant: AcOEt/PE: 10/90).
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