[NH2:1][C:2]1[C:10]([C:11]([CH3:14])([CH3:13])[CH3:12])=[CH:9][CH:8]=[CH:7][C:3]=1[C:4](O)=[O:5].C(O)(=O)C.[CH:19](N)=[NH:20].C(N)=O.[OH-].[Na+]>C(O)C>[C:11]([C:10]1[CH:9]=[CH:8][CH:7]=[C:3]2[C:2]=1[N:1]=[CH:19][NH:20][C:4]2=[O:5])([CH3:14])([CH3:13])[CH3:12]Procedure analogous to M. Berg et al., Chem. Med. Chem. 2009, 4, 2, 249: a mixture of 19.3 g (100 mmol) of 2-amino-3-tert-butylbenzoic acid [917874-35-2], 31.4 g (300 mmol) of formamidine acetate [3473-63-0] and 4.4 ml (110 mmol) of formamide is stirred at 160° C. for 12 h. After cooling to 60° C., a mixture of 200 ml of ethanol and 200 ml of 2 N sodium hydroxide solution is added dropwise, the mixture is filtered through a P4 frit covered with sea sand in order to remove polymeric material and then rendered neutral by addition of 2 N hydrochloric acid. After stirring for 12 h, the crystals formed are filtered off with suction and washed three times with 100 ml of water each time. Yield: 13.9 g (68 mmol), 68%. Purity: >95% according to 1H-NMR.
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