Ethanol → Ethyl 2-[(tetrahydro-2H-pyran-4-yl)oxy]acetate

To a solution of tetrahydro-4H-pyran-4-one (1.0 g, 10.0 mmol) in cold (0° C.) THF is added 1.0M lithium aluminum hydride in THF (5 mL, 5.0 mmol). The reaction mixture is stirred at 0° C. for 15 min. followed by the sequential addition of water (0.190 mL), 5M sodium hydroxide (0.190 mL), and water (0.190 mL) and Et2O. The mixture is filtered, and the filtrate is evaporated to give tetrahydro-4H-pyran-4-ol, which is dissolved in dichloromethane (30 mL). To the solution is added rhodium (II) acetate dimer (44 mg) followed by ethyl diazoacetate (1.25 g, 11.0 mmol). The reaction mixture is stirred at RT for 40 min. The reaction mixture is diluted with ethanol, filtered through Celite, and the filtrate is evaporated and the residue is vacuum distilled at 150° C. to give 1.67 g of the product 409. 1H NMR (CDCl3) δ 4.21 (q, 2H), 4.11 (s, 2H), 3.95 (dt, 2H), 3.59 (m, 1H), 3.42 (dt, 2H), 1.91 (m, 2H), 1.62 (m, 2H), 1.28 (t, 3H); MS: m/z 189 (M++1).