C(OC(C1C(=O)NC2C=CSC=2C=1Cl)=O)C.[CH3:17][O:18][C:19]([C:21]1[S:22][CH:23]=[CH:24][C:25]=1[NH2:26])=[O:20].[CH3:27][O:28][C:29]1[CH:36]=[CH:35][C:32]([CH2:33]Cl)=[CH:31][CH:30]=1>>[CH3:27][O:28][C:29]1[CH:36]=[CH:35][C:32]([CH2:33][NH:26][C:25]2[CH:24]=[CH:23][S:22][C:21]=2[C:19]([O:18][CH3:17])=[O:20])=[CH:31][CH:30]=1The preferred intermediate in the preparation of compounds of structure (I), 7-chloro-5-oxo-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester depicted by formula (4) below, was also prepared by an alternative route as shown in Scheme 34. In this method, methyl-3-amino-thiophene-2-carboxylate was reacted with 4-methoxy benzylchloride to yield methyl 3-(4-methoxybenzylamino)thiophene-2-carboxylate, depicted by formula (65). This intermediate was reacted with ethylmalonyl chloride followed by a cyclization reaction to yield 7-hydroxy-4-(4-methoxybenzyl)-5-oxo-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester, depicted by formula (67). Chlorination of 7-hydroxy-4-(4-methoxybenzyl)-5-oxo-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester, depicted by formula (67) by reacting with oxalyl chloride followed by deprotection yielded the intermediate 7-chloro-5-oxo-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester, depicted by formula (4), as shown in Scheme 34.
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