Methyl chloroformate → 2-Propyl-4-(((2-tetrahydropyranyl)oxy)methyl)oxazole-5-carboxylic acid, methyl ester

To a solution of 5-bromo-2-propyl-4-(((2-tetrahydropyranyl)oxy)methyl)oxazole (2.376 g, 7.82 mmol), prepared as in Example 29c, in 60 mL of THF and cooled to -78° C. was added n-buthylithium (8.75 mmol). The resulting solution was stirred for 30 minutes at -78° C., and 1.0 mL (12.9 mmol) of methyl chloroformate was added. The reaction mixture was stirred at -78° C. for 5 minutes and at 0° for 30 minutes. The reaction was quenched by the addition of satd NaHCO3, the layers were separated, and the aqueous layer extracted with methylene chloride. The organic extracts were combined, dried, and concentrated. The residue was chromatographed on silica gel, eluting with 10 to 25% ethyl acetate in hexane, to afford 1.660 g of the title compound as an oil. MS m/z: 284 (M+H)+. NMR (CDCl3) δ:4.95 (d, J=12 Hz, 1H), 4.82 (t, J=3 Hz, 1H), 4.67 (d, J=12 Hz, 1H), 3.94 (m, 1H), 3.92 (s, 3H), 3.57 (m, 1H), 2.80 (t, J=7.5 Hz, 2H), 1.84 (sextet, J=7.5 Hz, 2H), 1.80-1.50 (m, 6H), 1.05 (t, J=7.5 Hz, 3H).