反应详情

To a solution of zinc chloride (274 mg, 2.0 mmol) in THF (4 mL) was added (2-(1,3-dioxan-2-yl)ethyl)magnesium bromide (8.8 mL, 4.4 mmol, 0.5M THF) to provide bis(2-(1,3 dioxan-2-yl)ethyl)zinc. In a separate reaction vessel, a mixture of compound 1C (348.6 mg, 1.0 mmol) and potassium carbonate (276 mg, 2.0 mmol) in DMF (5 mL) was stirred at rt for 3 h. After this time, argon was bubbled through the mixture for 5 minutes and then the bis(2-(1,3 dioxan-2-yl)ethyl)zinc and Pd(dppf)Cl2[CH2Cl2] (81.7 mg, 0.10 mmol) were added. Upon completion of addition, the reaction vessel was flushed with argon, capped, and then heated at 90° C. for 16 h. After this time, the reaction mixture was partitioned between diethyl ether and water and stirred vigorously for 15 minutes. The organic phase was separated, dried over Na2SO4 and concentrated in vacuo to yield a residue. The residue was purified via flash chromatography (SiO2, 0-100% ethyl acetate/hexanes) followed by purification via preparative HPLC (Phenomenex Axia Luna column (30×100 mm); 0-100% B over 15 min, then 3 min B hold @40 mL/min; Solvent A=10% MeCN, 90% H2O; Solvent B=90% MeCN, 10% H2O) to afford compound 4A (289 mg, 75%) as a pale-yellow foam. LC/MS (m/z)=384 (M+H)+.