Iodine → Tetrahydro-2-(17-acetoxyheptadecyloxy)-2H-pyran

関与物質

反応手順

In a 50-ml flask, zinc powder (98 mg, 1.5 mmol) was dried at 70° C. under high vacuum for 30 min. After back-filling with nitrogen, DMI (25 ml) was added followed by solid I2 (380 mg, 1.53 mmol) for Zn activation. The iodine color disappeared after stirring for 5 min. Neat 6-bromohexyl acetate (6.83 g, 30.61 mmol) was added and the mixture was stirred at 65-80° C. for 2-14 h, cooled to the room temperature, excess zinc was allowed to settle, and the organozinc solution 46 was transferred via cannula into a solution of anhydrous LiBr (5.32 g, 61, 23 mmol) in THF (50 ml). The solution of organozinc reagent in DMI-THF mixture was cooled to 0° C. and solution of PEPPSI-IPr (130 mg, 0.191 mmol) in DMI (3 ml) was added followed by a rapid addition of neat Br(CH2)11OTHP 47 (6.42 g, 19.13 mmol). The cooling bath was removed and the reaction mixture was stirred at room temperature for 9 h. Reaction mixture was quenched with aqueous NH4Cl solution (250 ml) and extracted with EtOAc (250 ml). The extract was washed with aqueous NH4Cl solution, dried over Na2SO4 and concentrated under reduced pressure. The crude product was chromatographed on silica gel in hexane-EtOAc (97:3) to give the compound 39 (7.09 g, 93%).

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