Methanol → Ethyl (2S,4S)-4-methyl-3-[5-methyl-2-(2H-1,2,3-triazol-2-yl)benzoyl)-1,3-oxazinane-2-carboxylate

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Reaction Steps

To a solution of (3R)-3-aminobutanoic acid (1.0 g, 9.7 mmol) in THF (10 mL), a solution of borane-THF in 0.9 mol/L (32.3 mL, 29.1 mmol) was added dropwise under cooling in an ice bath over a period of 1 hour, and the resulting mixture was stirred for 20 minutes at room temperature. The resulting mixture was heated to 80° C. and further stirred with heating for 6 hours. Methanol was added thereto under cooling in an ice bath, the reaction mixture was stirred for 30 minutes and then concentrated under reduced pressure. By using the obtained (3R)-3-aminobutan-1-ol, ethyl glyoxylate (polymer type, a solution of 47% toluene) (2.0 mL, 9.7 mmol) and 5-methyl-2-(2H-1,2,3-triazol-2-yl)benzoic acid (0.50 g, 2.5 mmol), the same procedure as in Reference Example 1 was carried out to obtain a diastereomer mixture (colorless oil). The obtained diastereomer mixture was purified by column chromatography (HP-Sil 10 g, hexane/EtOAc=90/10 to 0/100) to obtain the title compound (0.37 g), which was a low polar compound (colorless oil).

Provenance & Evidence