Lawesson's reagent → 2-((1R)-1-(tert-Butoxycarbonylamino)-2-(2-naphthyl)ethyl)-5-phenyl-1,3-thiazole-4-carboxylic acid methylester

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Reaction Steps

2-((2R)-2-tert-Butoxycarbonylamino-3-(2-naphthyl)propionylamino)-3-oxo-3-phenylpropionic acid methylester (2.2 g; 4.069 mmol) and 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide (Lawesson's reagent) (4.1 g; 10.17 mmol) were refluxed 6 hours in 50 ml tetrahydrofuran. The solvent was removed in vacuo and the residue was chromatographed on silica; (4×40 cm) using ethyl acetate/heptane (1:1) as eluent and the residue was recrystalised from ethyl acetate/heptane (1:1; 50 ml) to afford 1.45 g of 2-((1R)-1-(tert-butoxycarbonylamino)-2-(2-naphthyl)-ethyl)-5-phenyl-1,3-thiazole-4-carboxylic acid methyl ester.

Provenance & Evidence