C(O[CH2:5][CH2:6][CH2:7][CH2:8][C@@H:9](O)[C:10]1[CH:11]=[N:12][CH:13]=[CH:14][CH:15]=1)(=S)C.C(N(CC)CC)C.C[S:25](Cl)(=O)=O.C[O-].[Na+]>ClCCl.CO>[N:12]1[CH:13]=[CH:14][CH:15]=[C:10]([C@@H:9]2[CH2:8][CH2:7][CH2:6][CH2:5][S:25]2)[CH:11]=1A solution of (R)-5-hydroxy-5-(3-pyridyl)pentyl thioacetate (10.0 g) in dichloromethane (200 ml) under nitrogen is cooled to 0° C. and treated with triethylamine (7 ml), followed by methanesulphonyl chloride (3.8 ml), dropwise between -5° C. and 0° C., during 5 minutes. The reaction mixture is then warmed to room temperature. After 60 minutes the mixture is cooled to 10° C. and treated, dropwise during 10 minutes, with a solution of sodium methoxide in methanol (20 ml; 25% w/v). The mixture is allowed to warm to room temperature. After 30 minutes the mixture is washed with water until the pH is between 9 and 10, dried over magnesium sulphate, evaporated and chromatographed, to give (S)-2-(3-pyridyl)tetrahydro-2H-thiopyran (7.5 g; 91% ee), in the form of an amber oil.
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