[CH2:1]([O:3][C:4]([N:6]([CH2:12][C:13]1[S:14][CH:15]=[CH:16][CH:17]=1)[CH2:7][CH2:8][C:9]([OH:11])=O)=[O:5])[CH3:2].C(Cl)(=O)C(Cl)=O.C(N)C1C=CC=CC=1.[Cl-].[Al+3].[Cl-].[Cl-].C(=O)(O)[O-].[Na+]>C(Cl)Cl.CN(C=O)C.CO>[O:11]=[C:9]1[CH2:8][CH2:7][N:6]([C:4]([O:3][CH2:1][CH3:2])=[O:5])[CH2:12][C:13]2[S:14][CH:15]=[CH:16][C:17]1=2To a solution of Compound 1042 (5.0 g, 19.43 mmol) in methylene chloride (200 mL) containing one drop of DMF at 0° C. was added oxalyl chloride (2.03 mL, 23.32 mmol). The reaction mixture was stirred at RT until LCMS analysis (after a benzyl amine quench of the aliquot to be analyzed) indicated complete conversion to the intermediate acyl chloride. The reaction was concentrated by 50%, at which point solid aluminum chloride (5.18 g, 38.86 mmol) was added. The reaction was then stirred at room temperature overnight. The reaction was cooled to 0° C. and methanol (50 mL) carefully added. After gas evolution had ceased, 100 mL of saturated sodium bicarbonate was added carefully. After gas evolution had ceased the reaction was extracted with 10% n-BuOH in chloroform, concentrated, and the residue purified by silica chromatography (0-50% ethyl acetate/hexanes) to give ethyl 4-oxo-5,6-dihydro-4H-thieno[2,3-c]azepine-7(8H)-carboxylate (Compound 1043) as a pale tan oil (1.27 g, 27%).
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