[H-].[Na+].[C:3]([O:7][C:8]([N:10]1[CH2:24][C@@H:23]([CH3:25])[N:13]2[C:14]3[CH:15]=[C:16]([CH2:21][OH:22])[CH:17]=[CH:18][C:19]=3[CH2:20][C@@H:12]2[CH2:11]1)=[O:9])([CH3:6])([CH3:5])[CH3:4].I[CH3:27]>CN(C)C=O>[C:3]([O:7][C:8]([N:10]1[CH2:24][C@@H:23]([CH3:25])[N:13]2[C:14]3[CH:15]=[C:16]([CH2:21][O:22][CH3:27])[CH:17]=[CH:18][C:19]=3[CH2:20][C@@H:12]2[CH2:11]1)=[O:9])([CH3:6])([CH3:4])[CH3:5]Sodium hydride (55–65% dispersion in mineral oil, 27 mg, 0.67 mmol) was added to a solution of (4R,10aR)-7-hydroxymethyl-4-methyl-3,4,10,10a-tetrahydro-1H-pyrazino[1,2-a]indole-2-carboxylic acid tert-butyl ester (200 mg, 0.63 mmol) in N,N-dimethylformamide (5 mL) at r.t., then after 1 h iodomethane (89 mg, 0.63 mmol) was added and the reaction mixture was stirred 2 h at 50° C. After cooling another portion of sodium hydride (27 mg, 0.67 mmol) was added, then after the addition of a second equivalent of iodomethane (89 mg, 0.63 mmol) the reaction mixture was stirred 2 h at 50° C. After cooling the reaction mixture was poured onto ice and extracted with ether (30 mL), the organic layer was washed with half-saturated brine, dried (MgSO4), and concentrated. Chromatography on SiO2 (Hexane/EtOAc 3:1) yielded the title compound (109 mg, 52%). Light yellow oil, ISP-MS: m/e=333.3 ([M+H]+).
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