C(NC(C)C)(C)C.C([Li])CCC.CCCCCC.[Cl:19][C:20]1[C:29]2[CH2:28][CH2:27][CH2:26][CH2:25][C:24]=2[N:23]=[CH:22][CH:21]=1.[C:30]1([Se:36]Cl)[CH:35]=[CH:34][CH:33]=[CH:32][CH:31]=1>O1CCCC1>[Cl:19][C:20]1[C:29]2[CH2:28][CH2:27][CH2:26][CH:25]([Se:36][C:30]3[CH:35]=[CH:34][CH:33]=[CH:32][CH:31]=3)[C:24]=2[N:23]=[CH:22][CH:21]=1A solution of diisopropylamine (18.5 ml, 132 mmol) in tetrahydrofuran (100 ml) at 0° was treated with 1.5M butyllithium solution in hexane (88 ml, 132 mmol) under an atmosphere of nitrogen, stirred for 10 min, cooled to -78°, treated dropwise with the product of Step 2 (7.35 g, 44 mmol) in tetrahydrofuran (50 ml) at <-65°, stirred at -78° for 20 min, treated with phenylselenyl chloride (8.5 g, 44 mmol) in tetrahydrofuran (50 ml), warmed to room temperature, and quenched with saturated aqueous ammonium chloride (250 ml). The reaction was worked-up in a similar way to that described in Example 25, Step 1 and the product (9 g) isolated by chromatography [silica; hexane-ether (2:1)] as an oil.
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