tert-Butyl hydrogen [2-methyl-1-(5-methyl-4-oxo-4H-3,1-benzoxazin-2-yl)propyl]carbonimidate → HCID 23437569, compound

Participants

Reaction Conditions

Reaction Steps

66.7 ml of 4N hydrochloric acid-1,4-dioxane solution was added dropwise to a solution of 9.31 g of 2-{1(S)-[(tert-butoxycarbonyl)amino]-2-methylpropyl}-5-methyl-4H-3,1-benzoxazin-4-one in 50 ml of 1,4-dioxene with stirring at 0° C. After stirring at 0° C. for 0.75 hour, the reaction mixture was concentrated. 6.25 g of fluorene-Δ9, α -acetic acid was added to the residue and dissolved in 150 ml of N,N-dimethylformamide. Then, 3.3 ml of N-methylmorpholine, 4.72 g of 1-hydroxybenzotriazole, and 5.91 g of water-soluble carbodiimide hydrochloride were successively added to the resultant solution under ice-cooling. After stirring at room temperature for 18 hours, the reaction solution was condensed, and the residue was purified by a silica gel column chromatography (eluting solution: methylene chloride-ether), followed by recrystallization from chloroform-hexane to give 5.76 g of 2-{1(S)-[(fluorene-Δ9, α -acetyl) amino]-2 -methylpropyl}-5-methyl-4H-3,1-benzoxazin-4-one: mp 223.5°-224.3° C., (see Table 1).

Provenance & Evidence