(3aR,5S)-5-methyl-3a,4,5,7-tetrahydro-3H-pyrano[3,4-c][1,2]oxazole

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

Procedure: To a solution of C5 (8.6 g, 0.06 mol) and triethylamine (0.455 g, 4.50 mmol) in dichloromethane (150 mL) at room temperature was slowly added a 6% aqueous solution of sodium hypochlorite (90 mL) while maintaining the internal temperature between 20° C. and 25° C. After the addition, the organic phase was separated, dried and concentrated in vacuo Silica gel chromatography (petroleum ether/ethyl acetate=10:1) provided the product as a yellow oil. Yield: 5.70 g, 40.4 mmol, 67%. LCMS m/z 142.1 [M+H+], 1H NMR (400 MHz, CDCl3), δ 4.68 (d, J=13.2 Hz, 1H), 4.59 (dd, J=10, 8 Hz, 1H), 4.18 (d, J=13.2 Hz, 1H), 3.76 (dd, J=12, 8 Hz, 1H), 3.59-3.66 (m, 1H), 3.39-3.50 (m, 1H), 2.14-2.19 (m, 1H). 1.42-1.51 (m, 1H), 1.25 (d, J=6 Hz, 3H). while maintaining the internal temperature between 20° C. and 25° C After the addition the organic phase was separated dried concentrated in vacuo Silica gel chromatography (petroleum ether/ethyl acetate=10:1)