C(NC(C)C)(C)C.C([Li])CCC.[CH2:13]1[C:17]2([CH2:22][CH2:21][CH2:20][CH:19]=[C:18]2[C:23](=[O:25])[CH3:24])[CH2:16][CH2:15][CH2:14]1.[CH:26](=[O:28])[CH3:27].[NH4+].[Cl-]>O1CCCC1>[OH:28][CH:26]([CH3:27])[CH2:24][C:23]([C:18]1[C:17]2([CH2:22][CH2:21][CH2:20][CH:19]=1)[CH2:13][CH2:14][CH2:15][CH2:16]2)=[O:25]At −70° C., a solution of diisopropylamine (40.9 g, 0.4 mol) in tetrahydrofuran (200 ml) was treated within 10 min. with n-butyl lithium (271 ml, 1.6M in hexane, 0.437 mol). The resulting solution was stirred at −40° C. for 20 min., cooled to −78° C., and treated within 20 min. with a solution of 1-(spiro[4.5]dec-6-en-6-yl)ethanone (62 g, 0.35 mol). The resulting solution was stirred 20 min. at −70° C. and treated with a solution of acetaldehyde (76.6 g, 1.75 mol) in tetrahydrofuran (100 ml). After 90 min. stirring, the reaction mixture was poured into a cold saturated aqueous solution of NH4Cl (400 ml) and extracted twice with MTBE (400 and 200 ml). The combined organic phases were washed with a water (200 ml), and twice with a saturated solution of NaCl, dried (MgSO4), and concentrated to give the desired intermediate 3-hydroxy-1-(spiro[4.5]dec-6-en-6-yl)butan-1-one (97.8 g) which was dissolved in acetic anhydride (70 ml, 0.73 mol). The resulting solution was treated with sodium acetate (31.4 g, 0.383 mol), heated at 80° C. for 8 h, treated with sodium acetate (10 g, 0.122 mol), heated at 80° C. for 15 h, treated with sodium acetate (10 g, 0.122 mol), heated at 80° C. for 2 h. The reaction mixture was cooled to 0° C., poured into ice/water and extracted three times with MTBE (200 ml). The combined organic phases were washed with 2N aqueous NaOH (300 ml), with a saturated aqueous NaCl solution (250 ml), dried (30 g MgSO4) and concentrated. Short-path Vigreux distillation (0.08 mbar, bath temperature 140-180° C., head temperature: 80-146° C.) of the crude product (89.6 g) followed by distillation (0.08 mbar, bath temperature 150-180° C., head temperature: 98° C.) using a microdistillation column (20×1.5 cm, filled with 3×3 mm rolled wire netting) gave (E)-1-(spiro[4.5]dec-6-en-6-yl)but-2-en-1-one (55.6 g, 58%).
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