[CH3:1][NH:2][S:3]([CH2:6][CH3:7])(=[O:5])=[O:4].[H-].[Na+].[CH3:10][C:11]1([CH3:22])[O:20][C:19]2[C:14](=[CH:15][N:16]=[CH:17][CH:18]=2)[CH:13]2[O:21][CH:12]12.CCCCCCC>CS(C)=O.C(OCC)(=O)C>[OH:21][CH:12]1[C:11]([CH3:22])([CH3:10])[O:20][C:19]2[CH:18]=[CH:17][N:16]=[CH:15][C:14]=2[CH:13]1[CH2:1][NH:2][S:3]([CH2:6][CH3:7])(=[O:5])=[O:4]A solution of 480 mg (3.5 mmol) of N-methylethylsulfonamide in 0.75 ml DMSO (dimethylsulfoxide) is added to a suspension of 27 mg (0.7 mmol) of NaH (60% strength) in 1.5 ml of DMSO. After stirring at room temperature for 2 h, a solution of 0.48 g (2.7 mmol) of 2,2-dimethyl-1a,7b-dihydro-2H-1,3-dioxa-6-aza-cyclo-propa[a]naphthalene (prepared analogously to G. Burell et al. J. Med. Chem. 33 (1990) 3023-3027) in 6 ml of DMSO is added dropwise. The mixture is heated at 60° C. for 4 h and then stirred overnight at room temperature. The reaction mixture is added to ice water and extracted with ethyl acetate. After removing the solvent in vacuo, the solid obtained is stirred with a mixture of heptane and ethyl acetate and filtered off with suction. 400 mg (67%) of ethanesulfonic acid (3-hydroxy-2,2-dimethyl-3,4-dihydro-2H-pyrano[3,2-c]pyridin-4-yl)methylamide are obtained as a solid (m.p. 163° C.).
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