[Cl-].CON(C)[C:5](=[O:16])[CH2:6][C:7]1[C:12]([F:13])=[CH:11][CH:10]=[C:9]([F:14])[C:8]=1[F:15].Cl.[CH3:19]C(OC)(C)C>C1COCC1>[F:15][C:8]1[C:9]([F:14])=[CH:10][CH:11]=[C:12]([F:13])[C:7]=1[CH2:6][C:5](=[O:16])[CH3:19]
A mixture of CeCl3 (438 g, 1779 mmol) and THF (12 L) was heated at 40° C. for about 2 h then cooled to 5° C. Methylmagensium chloride in THF (3 M, 3.4 L) was charged at 5-9° C. and then it was warmed up to 16° C. and held for 1 h. The suspension was re-cooled to −10 to −15° C. A solution of 17 (1.19 kg) in THF (2.4 L) was charged into the suspension over 15 min. After confirmation of completion of the reaction, the reaction mixture was transferred to a cold solution of hydrochloric acid (2 N, 8.4 L) and MTBE (5 L) in 5-10° C. The aqueous phase was separated and the organic layer was washed with aqueous 5% K2CO3 (6 L) and then 10% aqueous NaCl (5 L). The organic layer was dried over Na2SO4, concentrated to give crude 18 (917 g, >99 wt %) in 95% yield. The crude 18 was used in the next step without further purification. Analytically pure 18 was obtained by silica gel column.
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