Trifluoroacetic acid → HCID 14011750, compound

Participants

Reaction Steps

A mixture of trifluoroacetic acid (8 ml.) and anisole (0.4 ml.) is cooled in an ice-water bath under nitrogen and treated with (5R)-5[[1-(ethoxycarbonyl)-3-phenylpropyl]amino]dihydro-4-oxo-2-phenyl-2H-1,3-thiazine-3(4H)-acetic acid, 2-(trimethylsilyl)ethyl ester (B-slow isomer) (400 mg., 0.72 mmole) dissolved in dry methylene chloride (4 ml.). The cooling bath is removed and the reaction is stirred at ambient temperature for 3 hours, then concentrated in vacuo and azeotroped with toluene. The crude product (440 mg.) is chromatographed on 150 ml. of HP-20 eluted with a gradient from 400 ml. of water:acetonitrile (5:4) to 400 ml. of 100% acetonitrile. The product containing fractions are pooled, evaporated, then precipitated from ethanol (10 ml.) by the addition of water (300 ml.). By this method 171 mg. of (5R)-5-[[1-(ethoxycarbonyl)-3-phenylpropyl]amino]dihydro-4-oxo-2-phenyl-2H1,3-thiazine-3(4H)-acetic acid (B-slow isomer) are obtained; m.p. 130°-135°; [α]D =-36.1° (c=1, methanol). TLC (ethyl acetate:pyridine:acetic acid: water; 100:20:6:11) spot at Rf =0.79.

Provenance & Evidence