[CH:1]([N-]C(C)C)(C)C.[Li+].C(C1C=CC=CC=1)C.CCCCCCC.[CH3:24][O:25][C:26](=[O:41])[CH2:27][C:28]1[CH:29]=[CH:30][C:31]2[S:35][C:34]([CH2:36][CH:37]([CH3:39])[CH3:38])=[N:33][C:32]=2[CH:40]=1.CI>O1CCCC1>[CH3:39][CH:37]([CH3:38])[CH2:36][C:34]1[S:35][C:31]2[CH:30]=[CH:29][C:28]([CH:27]([CH3:1])[C:26]([O:25][CH3:24])=[O:41])=[CH:40][C:32]=2[N:33]=1
A solution of lithium diisopropylamide (2.0M solution in tetrahydrofran/ethylbenzene/heptane, 2.09 ml, 0.0042 mol) was added, dropwise, to a solution of methyl[2-(2-methylpropyl)benzothiazol-5-yl]acetate (1.1 g, 0.0042 mol) in tetrahydrofuran (27 ml) at −78° C. under a nitrogen atmosphere and the mixture was stirred at below −60° C. for 1 hour. Methyl iodide (2.29 ml, 0.037 mol) was added, dropwise, and the mixture was stirred at below −60° C. for a further 1 hour. The cooling bath was removed and the mixture was allowed to warm to room temperature over a period of 1 hour. The mixture was diluted with water, acidified with 2M aqueous hydrochloric acid and extracted with ethyl acetate. The organic extract was dried over anhydrous magnesium sulfate, filtered and the filtrate evaporated in vacuo to give methyl 2-[2-(2-methylpropyl)benzothiazol-5-yl]propionate (1.15 g) which was used without further purification in the next step.
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