[C:1]([C:3]1([O:8][Si:9]([CH3:12])([CH3:11])[CH3:10])[CH2:7][CH2:6][CH2:5][CH2:4]1)#[CH:2].[Li]CCCC.CON(C)[C:21](=[O:28])[C:22]1[CH:27]=[CH:26][N:25]=[CH:24][CH:23]=1>C1COCC1>[N:25]1[CH:26]=[CH:27][C:22]([C:21](=[O:28])[C:2]#[C:1][C:3]2([O:8][Si:9]([CH3:10])([CH3:12])[CH3:11])[CH2:7][CH2:6][CH2:5][CH2:4]2)=[CH:23][CH:24]=1To a stirred solution of (1-ethynylcyclopentyloxy)trimethylsilane (2.0 g, 11.0 mmol) in dry THF (50 mL) was added n-BuLi (20.0 mL, 20.0 mmol, 1.6 M in hexane) drop wise at −78° C. under an inert atmosphere for a period of 10 min. After being stirred for 30 min at −78° C., a solution of compound N-methoxy-N-methylisonicotinamide (2.1 g, 13.2 mmol) in dry THF (10 mL) was added to the reaction mixture and stirring was continued for an additional 2 h at −78° C. The reaction mixture was quenched with a saturated NH4Cl solution and extracted with EtOAc (2×60 mL). The combined organic layers were washed with water (20 mL), brine (20 mL), dried over Na2SO4, filtered and concentrated in vacuo to obtain the crude product. The crude material was purified via silica gel column chromatography eluting with 5% EtOAc in Hexane to afford 1-(pyridin-4-yl)-3-(1-(trimethylsilyloxy)cyclopentyl) prop-2-yn-1-one (1.0 g, 32%) as an oil.
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