C(Cl)(=O)C(Cl)=O.[C:7]([N:14]1[CH2:19][CH2:18][CH:17]([CH2:20][CH2:21]O)[CH2:16][CH2:15]1)([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[O:8].CN1CCOCC1.[CH3:30][O:31][C:32]([CH:34]=P(C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)=[O:33]>C(Cl)Cl.CS(C)=O>[C:7]([N:14]1[CH2:15][CH2:16][CH:17]([CH2:20]/[CH:21]=[CH:34]/[C:32]([O:31][CH3:30])=[O:33])[CH2:18][CH2:19]1)([O:9][C:10]([CH3:11])([CH3:12])[CH3:13])=[O:8]A solution of oxalyl chloride (11.8 g) in methylene chloride (180 ml) is cooled to −78° C. and dimethyl sulfoxide (DMSO) (8.9 ml) is added dropwise. The solution is stirred at −78° C. for about 3 minutes and a solution of N-BOC-2-(piperidin-4-yl)ethanol (14.3 g) in methylene chloride (250 ml) is added over a period of about 10 minutes. The solution is stirred for about 1 hour and N-methyl morpholine (21.6 g) is added over a period of about 15 minutes. The solution is allowed to warm to room temperature and, after about 30 minutes, methyl (triphenylphosphoranylidene) acetate (68.6 g) is added. The solution is stirred at room temperature for about 18 hours, evaporated in vacuo and the residue taken up in ethyl acetate. The ethyl acetate solution is washed with water, 5% HCl, 5% sodium hypochlorite solution, water, brine, dried over sodium sulfate, filtered and evaporated in vacuo to give methyl 4-(N-BOC-piperidin-4-yl)trans-crotonate.
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