Trifluoroacetic acid → (R)-methyl 1-methoxy-2-oxo-1,2,3,4-tetrahydroquinolin-3-ylcarbamate

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Reaction Steps

A suspension of (R)-N-methoxy-2-(methoxycarbonylamino)-3-phenylpropanamide (III, EXAMPLE 2, 11.25 g, 44.6 mmol) in dichloromethane (170 ml) is cooled in an ice bath and trifluoroacetic acid (9.25 ml, 13.7 g, 0.120 mol) is added. Bis(trifluoroacetoxy)iodobenzene (19.78 g, 0.046 mol) is added portion wise over 10 min at 0°, and the mixture is stirred at this temperature for one hour. The mixture is washed with sodium carbonate mixture (10%) and dried over magnesium sulfate. The solvent is removed under reduced pressure to give a concentrate. Purification by flash chromatography (230-400 mesh silica gel, 40-50% ethyl acetate/hexane) gives the desired product. An analytical sample is crystallized from ethyl acetate/hexane to give the title compound, mp=117-119°; NMR (CDCl3) 2.85, 3.44, 3.72, 3.93, 4.42, 5.82, 7.09, 7.33 and 7.22 δ; IR (mineral oil) 1722 and 1703 cm−1; [a]25D=+34.20 (CH3OH, c=0.927).

Provenance & Evidence