(3S)-3-methoxyoxan-4-one

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 5-L 4-neck round bottom flask equipped with a overhead air stirrer, nitrogen inlet adapter, thermocouple, and septum was charged with (S)-3,4,4-trimethoxytetrahydro-2H-pyran (as prepared in the previous step, 83 g, 0.47 mol), THF (2.1 L), H2O (670 mL), and stirred in ice/acetone bath until <0° C., where upon a solution of HCl (conc., 350 mL, 4.24 mol) was added via addition funnel over 30 min while keeping temperature <2° C. After the addition was complete, the reaction was allowed to stir for 1 h at 0° C. The reaction was evaporated until ˜1.2 L of concentrate remained. The concentrate was transferred to a reparatory funnel and extracted with CH2Cl2 (3×750 mL). The combined organic fractions were washed with sat. NaHCO3 (500 mL), brine (500 mL), dried over MgSO4, filtered and evaporated to afford the title compound (46.9 g, 77%, Chiral GC 91% ee) as an oil which solidified upon sitting. Optical Rotation: [α]25(D)+3.65° (c=1.020, MeOH); Elemental Analysis calc for C6H10O3: C, 53.39; H, 7.57. Found: 53.59; H, 7.62. A 5-L 4-neck round bottom flask equipped with a overhead air stirrer, nitrogen inlet adapter temperature <2° C After the addition The reaction was evaporated until ˜1.2 L of concentrate The concentrate was transferred to a reparatory funnel extracted with CH2Cl2 (3×750 mL) The combined organic fractions were washed with sat. NaHCO3 (500 mL), brine (500 mL) dried over MgSO4 filtered evaporated