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According to the procedure for the preparation of 207d, 206a (78.0 g, 0.40 mol) was reacted with 3,4-dihydro-2H-pyran (41.5 g, 0.49 mol) and p-toluenesulfonic acid hydrate (0.42 g, 2.2 mmol) in CH2Cl2 (0.5 L) to yield 207a (101.0 g, 90%) as a pale-yellow oil, which was used without further purification. 1H NMR (CDCl3): δ 4.55 (t, 1H, J=2.9), 3.83 (m, 1H), 3.51 (m, 1H), 3.47 (d, 1H, J=9.0), 3.38 (t, 2H, J=6.8), 2.98 (d, 1H, J=9.0), 1.94-1.75 (m, 2H), 1.75-1.44 (m, 6H), 1.40 (t, 2H, J=8.5), 0.91 (s, 3H), 0.90 (s, 3H). 13C NMR (CDCl3): δ 99.01, 76.17, 61.85, 37.89, 34.66, 34.04, 30.62, 27.92, 25.60, 24.64, 24.56, 19.41. HRMS (LSIMS, nba): Calcd for C12H24BrO2 (MH+): 279.0960, found: 279.0955.