Oxalyl chloride → 6-[(2R,6S)-2,6-dimethylmorpholin-4-yl]-7-methyl-3-(1,3-thiazol-2-yl)-1,2-benzoxazole-5-carbaldehyde

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Reaction Steps

Oxalyl chloride (0.31 g, 2.4 mmol) was added to a stirred solution of 6-[(2R,6S)-2,6-dimethylmorpholin-4-yl]-7-methyl-3-(1,3-thiazol-2-yl)-1,2-benzoxazole-5-carboxylic acid (Intermediate 326, 0.18 g, 0.4 mmol) and two drops DMF in dichloromethane (5 mL) at 0° C. and the mixture was stirred at room temperature for 2 hours. Solvent was removed under reduced pressure and the residue was dissolved in THF (10 mL) and the solution was cooled to −78° C. and 1M solution of lithium tri(t-butoxy)aluminum hydride (0.28 g, 1.1 mmol) was added slowly and it was stirred for 30 mins at the same temperature. The reaction was quenched with 1.5N hydrochloric acid and extracted with ethyl acetate, the combined organic layers were dried over sodium sulfate and the solvent was removed. The brown viscous oil thus obtained was purified by silica gel column chromatography (20% ethyl acetate in hexane) affording the product as yellow solid. Yield: 0.06 g (35%).

Provenance & Evidence