Lithium diisopropylamide → 3-(2,6-Dichloro-4-methoxy-benzyl)-1-(1,4-dioxa-spiro[4.5]dec-8-yl)-pyrrolidin-2-one

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Cool a solution of 1-(1,4-Dioxa-spiro[4.5]dec-8-yl)-pyrrolidin-2-one (5 g, 22.2 mmol) in tetrahydrofuran (100 mL) to −78° C. under nitrogen purge. Add LDA (2.0 M, 15 mL, 30 mmol) at a rate such that the internal reaction temperature did not reach above −67° C. Stir 30 min at −78° C., add a solution of 2-bromomethyl-1,3-dichloro-5-methoxy-benzene, 6.6 g, 24.4 mmol) in THF (20 mL) over a 1-2 minute period, remove the cold bath and allow reaction to warm over 3 hr. Quench the reaction with saturated aqueous ammonium chloride (100 mL), extract with ethyl acetate (3×100 mL), combine the extracts and dry over anhydrous sodium sulfate. Purify on silica column eluting with 8:2 hexanes:ethyl acetate to 1:1 hexanes:ethyl acetate to afford the product as a ivory solid, 6.5 g, 71%. 1H NMR (CDCl3) δ 6.86 (s, 2H), 4.06-4.12 (m, 1H), 3.94 (s, 4H), 3.77 (s, 3H), 3.32-3.41 (m, 2H), 3.15-3.21 (m, 1H), 2.83-2.97 (m, 2H), 1.68-2.04 (m, 8H). LCMS m+1 414.

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