Hydrochloric Acid → (R)-3-methoxydihydro-2H-pyran-4(3H)-one

Participants

Reaction Conditions

Reaction Steps

A stirred mixture of (R)-3,4,4-trimethoxytetrahydro-2H-pyran (as prepared in the previous step, 141 g, 0.80 mol), in THF (3.6 L) and H2O (1.1 L) in an ice/acetone bath at <0° C., was treated with a solution of HCl (conc., 595 mL, 7.21 mol) added via addition funnel over 45 min while keeping temperature <3° C. After the addition was complete, the reaction was allowed to stir for 1.5 h at 0° C. The reaction was evaporated until ˜1.9 L of concentrate remained. The concentrated was transferred to a separatory funnel and extracted with CH2Cl2 (3×1 L). The combined organic fractions were washed with sat. NaHCO3 (1 L), brine (1 L), dried over MgSO4, filtered and evaporated to afford the title compound (71.4 g, 69%, Chiral GC 92% ee) as an oil which solidified upon standing. Optical Rotation: [α]25(D) −6.97° (c=0.8222, MeOH); Elemental Analysis calc for C6H10O3: C, 53.59; H, 7.58. Found: C, 53.64; H, 7.65.

Provenance & Evidence