[CH3:1][CH:2]([CH3:14])[CH:3]([NH:6][C:7](=[O:13])[O:8][C:9]([CH3:12])([CH3:11])[CH3:10])[CH:4]=O.[N+](=[C:17](P(=O)(OC)OC)C(=O)C)=[N-].C(=O)([O-])[O-].[K+].[K+]>CO>[CH3:1][CH:2]([CH3:14])[CH:3]([NH:6][C:7](=[O:13])[O:8][C:9]([CH3:12])([CH3:11])[CH3:10])[C:4]#[CH:17]To a solution of 1.25 g of tert-butyl 3-methyl-1-oxobutan-2-ylcarbamate (Formula 21) and 1.79 g of dimethyl 1-diazo-2-oxopropylphosphonate (Formula 15) in 80 mL of methanol at 0° C. was added 1.72 g of potassium carbonate. The mixture was stirred at room temperature for 16 hours then quenched with saturated ammonium chloride solution and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over sodium sulfate and concentrated. Column chromatography (15% ethyl acetate/hexane) gave 1.01 g of tert-butyl 4-methylpent-1-yn-3-ylcarbamate (Formula 22) as a clear oil. 1H NMR (300 MHz, CDCl3) δ 0.98-1.00 (m, 6H), 1.45 (s, 9H), 1.87-1.93 (m, 1H), 2.24-2.25 (m, 1H), 4.32 (br, 1H).
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