N#N.C([SiH2][O:8][C:9](C)(C)[C:10]1[S:14][C:13]([C:15](=[O:17])[CH3:16])=[N:12][CH:11]=1)(C)(C)C.COC([O:25][CH3:26])OC.[C:27]([O-])([O-])=O.[Na+].[Na+]>C(O)CO>[CH3:16][C:15]1([C:13]2[S:14][C:10]([CH2:9][OH:8])=[CH:11][N:12]=2)[O:17][CH2:27][CH2:26][O:25]1In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a solution of 1-[5-(tert-butyl-dimethyl-silanyloxymethyl)-thiazol-2-yl]-ethanone (1.00 g, 3.68 mmol) in ethylene glycol (4 mL) was treated with trimethylorthoformate (0.82 mL, 7.51 mmol) followed by LiBF4 (70 mg, 0.74 mmol). The reaction mixture was heated at 95° C. for 2 days. Sat. aq. Na2CO3 (5 mL) was added and the mixture was extracted with Et2O (3×20 mL). The org. extracts were dried over Na2SO4, filtered, and the solvent was removed under reduced pressure. The crude residue (mixture of silylated/desilylated products) in dry THF (10 mL) was treated at rt with TBAF (1.1 mL of a 1M solution in THF, 1.10 mmol). The reaction mixture was stirred at rt until completion of the reaction. The mixture was then diluted with EA, washed with brine, dried over MgSO4, filtered and concentrated under reduced pressure. Purification of the residue by FC (4:1->1:2 hept-EA) gave the title compound as a pale yellow solid. TLC: rf (EA)=0.47. LC-MS-conditions 02: tR=0.60 min; [M+H]+=202.46.
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