Methanesulfonic Acid → 3,3-Dimethyl-8-(pyrrolidin-1-ylsulfonyl)-3,4-dihydropyrimido[1,2-a]indol-10(2H)-one
Reaction equation
[CH3:1][C:2]1([CH3:28])[CH2:27][N:6]2[C:7]3[CH:8]=[CH:9][C:10]([S:19]([N:22]4[CH2:26][CH2:25][CH2:24][CH2:23]4)(=[O:21])=[O:20])=[CH:11][C:12]=3[C:13]3(OCCC[O:14]3)[C:5]2=[N:4][CH2:3]1.CS(O)(=O)=O>>[CH3:1][C:2]1([CH3:28])[CH2:27][N:6]2[C:7]3[CH:8]=[CH:9][C:10]([S:19]([N:22]4[CH2:26][CH2:25][CH2:24][CH2:23]4)(=[O:20])=[O:21])=[CH:11][C:12]=3[C:13](=[O:14])[C:5]2=[N:4][CH2:3]1Participants
3
Conditions
- Temperature
- 60 °C
Procedure
To 3′,3′-dimethyl-8′-(pyrrolidin-1-ylsulfonyl)-3′,4′-dihydro-2′H-spiro[1,3-dioxane-2,10′-pyrimido[1,2-a]indole] (0.231 g, 0.570 mmol) was added methane sulfonic acid (6 mL) and the mixture was heated at 60° C. for 3 hr. The reaction was cooled to room temperature, poured onto ice, and basified with concentrated NH4O H to pH 11 keeping the reaction temperature below 5° C. The resulting orange solid was filtered, dissolved in CH2Cl2 and EtOAc, dried over Na2SO4, filtered, and concentrated to give the title compound as a bright yellow solid (0.155 g, 78% yield). Anal: Calc'd for C17H21N3O3S: C, 58.77; H, 6.09; N, 12.09. Found: C, 58.90; H, 6.20; N, 11.75. NMR (300 Mz, DMSO-d6): consistent. MS: (ES−) 346 [M−H]. MS: (ES+) 348 [M+H]. m.p.: 200-201° C.