[Br:1][C:2]1[CH:3]=[C:4]2[C:17](=[CH:18][CH:19]=1)[O:16][C:7]1([CH2:11][CH2:10][CH:9]([C:12]([CH3:15])([CH3:14])[CH3:13])[CH2:8]1)[CH2:6][C:5]2=O.C[Si]([N:25]=[C:26]=[N:27][Si](C)(C)C)(C)C>C(Cl)Cl.Cl[Ti](Cl)(Cl)Cl>[Br:1][C:2]1[CH:3]=[C:4]2[C:17](=[CH:18][CH:19]=1)[O:16][C:7]1([CH2:11][CH2:10][CH:9]([C:12]([CH3:15])([CH3:14])[CH3:13])[CH2:8]1)[CH2:6]/[C:5]/2=[N:27]\[C:26]#[N:25]To a solution of 6-bromo-3′-tert-butylspiro[chroman-2,1′-cyclopentan]-4-one (200 mg, 0.60 mmol) in dried CH2Cl2 (10 mL) was added TiCl4 (1 M solution in DCM, 1.20 mmol) dropwise within 15 minutes. The mixture was stirred for 1 h after addition. To this mixture was added bis-trimethylsilylcarbodiimide (244 mg, 1.31 mmol) dropwise. The resulting mixture was stirred for 18 h after addition. The reaction mixture was poured into ice-water (30 g) and extracted with CH2Cl2. The combined organic layer was washed with brine, dried over Na2SO4, filtered and concentrated to give (E)-N-(6-bromo-3′-tert-butylspiro[chroman-2,1′-cyclopentane]-4-ylidene)cyanamide (200 mg, crude), which was used for the next step without further purification.
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