Acetic Acid → N-methyl(3-methylbenzo[b]thiophen-2-yl)methanamine

HRID 1761095Notes

Reaction equation

HRID 1761095 reaction equation
[CH3:1][C:2]1[C:3]2[CH:12]=[CH:11][CH:10]=[CH:9][C:4]=2[S:5][C:6]=1[CH:7]=O.CN.CC(O)=O.[C:19]([BH3-])#[N:20].[Na+]>CO>[CH3:1][C:2]1[C:3]2[CH:12]=[CH:11][CH:10]=[CH:9][C:4]=2[S:5][C:6]=1[CH2:7][NH:20][CH3:19]

Participants

6

Reactant 4

HCID 176Acetic AcidHCID 6329MethylamineHCID 5199183-Methylbenzo(b)thiophene-2-carboxaldehydeHCID 5003444Sodium cyanoborohydride

Product 1

HCID 22593745N-methyl(3-methylbenzo[b]thiophen-2-yl)methanamineYield 56%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent2×

Procedure

To a stirred solution of 3-methylbenzo[b]thiophene-2-carboxaldehyde (0.5 g, 2.8 mmole) in methanol (15 mL) was added 2.0 M methylamine in methanol (6 mL, 12 mmole) and HOAc (0.32 mL, 5.7 mmole). The reaction was stirred at RT for hr, then sodium cyanoborohydride (0.2 g, 3 mmole) was added in one portion. After stirring for an additional 16 hr the reaction was concentrated to dryness. The residue was taken up in Et2O and washed with 1.0 N NaOH then with brine, dried (Na2SO4), and concentrated under vacuum. Purification by flash chromatography on silica gel (95:5 CHCl3/methanol containing 5% NH4OH) gave the title compound (0.30 g, 56%) as a yellow oil: 1H NMR (400 MHz, CDCl3) δ 7.77 (d, J=7.8 Hz,1H), 7.62 (d, J=7.9 Hz, 1H), 7.34 (t,1H), 7.28 (t,1H), 3.99 (s, 2H), 2.49 (s, 3H), 2.34 (s, 3H), 1.77 (br s,1H).

Workup

  1. stirringAfter stirring for an additional 16 hr the reaction
  2. concentrationwas concentrated to dryness
  3. washwashed with 1.0 N NaOH
  4. dry with materialwith brine, dried (Na2SO4)
  5. concentrationconcentrated under vacuum
  6. customPurification by flash chromatography on silica gel (95:5 CHCl3/methanol containing 5% NH4OH)

Sources & evidence

ORD record
ord-3f40522caf444bfc97e4483c66d9e747
Source dataset
uspto-grants-2005_01
Patent number
US06846819B1

Reaction notes

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