Hydrochloric Acid → (2R,3R,4S,5S)-N-heptyl-3-hydroxy-4-methoxy-5methyltetrahydro-2H-pyran-2-carboxamide

Participants

Reaction Conditions

Reaction Steps

A mixture of methyl (2R,3R,4S,5S)-3-benzyloxy-4-methoxy-5-methyltetrahydro-2H-pyran-2-carboxylate (7 mg, 0.024 mmole) and heptylamine (0.1 ml, 0.68 mmole) was heated at 90° C. for 3 hr. The reaction mixture was adjusted to pH 3 with 0.1N aqueous HCl, and partitioned between ether (10 ml) and water (10 ml). The ether layer was dried over anhydrous magnesium sulfate and evaporated to dryness under reduced pressure. A solution of the resulting crude amide in MeOH (5 ml) was stirred under hydrogen atmosphere in the presence of Pd-black (5 mg) at room temperature for 12 hr. The catalyst was removed by filtration and washed with methanol (2 ml×2). The combined filtrate and washings were evaporated to dryness under reduced pressure. The residue was chromatographed on silica gel using AcOEt/n-hexane (4:6) as an eluent to give (2R,3R,4S,5S)-N-heptyl-3-hydroxy-4-methoxy-5methyltetrahydro-2H-pyran-2-carboxamide (3.4 mg, 50% yield) as an oil; FAB-MS: m/z 288 (MH+). 1H-NMR (CDCl3)d: 0.91 (3H,t,J=6.5 Hz), 1.05 (3H,d,J=7 Hz), 1.25 (10H,br.s), 2.2 (1H, m), 3.10-3.6 (7H,br.m), 3.3 (3H,s), 3.81 (1H,dd,J=2.5 & 12 Hz), 8.0 (1H,br.s).

Provenance & Evidence