Acetyl chloride → Isohexane ethyl acetate

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Reaction Steps

Acetyl chloride (0.3 mL) was added dropwise to an ice-cooled solution of compound 7-3 (103.4 mg, 0.316 mmol) (see reference example 7) in methanol (2.9 mL). The solution was stirred at rt overnight, and then concentrated in vacuo, coevaporated twice with CH2Cl2, and dried under vacuum. Boc-L-leucine-H2O (96.2 mg, 0.386 mmol) and HATU (143 mg, 0.376 mmol) were added and the mixture was cooled in an ice bath. DMF (3.2 mL), followed by DIEA (220 μL, 1.26 mmol) were added. The resulting solution was stirred at rt for 6 h. The reaction mixture was concentrated in vacuo, redissolved in EtOAc (15 mL), and washed successively with saturated aqueous NaHCO3 (10 mL) and saturated aqueous NaCl (10 mL). The organic phase was dried (Na2SO4) and then concentrated in vacuo to give the crude material. Flash column chromatography (silica, 2/1 isohexane-EtOAc) gave compound 4i as white solids (127.8 mg, 92% yield).

Provenance & Evidence