[Br-].[CH2:2]([P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[CH2:3][CH3:4].[CH3:24]CCCCC.[H-].[Na+].[C:32]([O:36][C:37]([N:39]1[CH2:44][CH2:43][C:42](=O)[CH2:41][CH:40]1[C:46]([OH:48])=[O:47])=[O:38])([CH3:35])([CH3:34])[CH3:33]>C1COCC1.O>[CH3:24][O:48][C:46]([CH:40]1[CH2:41][C:42](=[CH:2][CH2:3][CH3:4])[CH2:43][CH2:44][N:39]1[C:37]([O:36][C:32]([CH3:35])([CH3:34])[CH3:33])=[O:38])=[O:47]
Propyltriphenylphosphonium bromide (1.24 g, 3.22 mmol) in THF (10 mL) was added to hexane washed sodium hydride (123 mg, 3.22 mmol), in THF (10 mL) and stirred at room temperature for 3 h. Methyl ester 12a (P=Boc, m=2, P2=Me) (0.55 g, 2.15 mmol) in THF (5 mL) was added to the above reaction mixture slowly and then allowed to stir for additional 2 h. It was then poured into water and extracted with ethyl acetate (30 mL). The organic phase was dried with magnesium sulfate, filtered and evaporated to dryness, the resulting residue was chromatographed using 20% EtOAc in hexanes to provide the product 4-propylidene-piperidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester. (0.100 g, 16%): MS (ESPOS): 284 [M+H]+; 1H NMR (300 MHz, CD3OD) δ 5.18 (m, m), 4.60-4.93 (m, 1), 3.91 (m, 1), 3.67 (s, 3), 2.94-3.04 (m, 2), 2.40-2.48 (m, 2), 1.99-2.06 (m, 1), 1.85-1.97 (m, 2), 1.38 (bs, 9), 0.85 (t, J=5 Hz, 3).
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