Formaldehyde → cyclopenta-1,3-diene;N,N-dimethylcyclopenta-2,4-dien-1-amine;iron(2+)

HRID 1014752Notes

Reaction equation

HRID 1014752 reaction equation
[NH2:1][C-:2]1[CH:6]=[CH:5][CH:4]=[CH:3]1.[CH-:7]1[CH:11]=[CH:10][CH:9]=[CH:8]1.[Fe+2:12].C=O.[BH3-][C:16]#N.[Na+].[OH-].[Na+]>C(O)(=O)C>[CH3:16][N:1]([C-:7]1[CH:11]=[CH:10][CH:9]=[CH:8]1)[CH3:2].[CH-:2]1[CH:6]=[CH:5][CH:4]=[CH:3]1.[Fe+2:12]

Participants

6

Reactant 4

HCID 712FormaldehydeHCID 14798Sodium HydroxideHCID 5003444Sodium cyanoborohydrideHCID 15501615Cyclopenta-2,4-dien-1-amine;cyclopenta-1,3-diene;iron(2+)

Product 1

HCID 129678476cyclopenta-1,3-diene;N,N-dimethylcyclopenta-2,4-dien-1-amine;iron(2+)Yield 182.1%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

A solution of aminoferrocene (1.07 g, 5.32 mmol) in acetic acid (15 mL) under argon was treated with paraformaldehyde (1.59 g, 53.2 mmol) and NaBH3CN (1.67 g, 26.6 mmol) and stirred at room temperature for 16 h. The reaction mixture was brought to pH 12 by addition of 6 M aqueous NaOH solution, and extracted with hexanes (3×20 mL). The combined organic extract was washed with water and brine, dried over anhydrous Na2SO4, filtered and concentrated to approx. 5% of its original volume under reduced pressure. The solution was filtered through basic alumina (20 mL) with hexanes, concentrated back to its pre-filtration volume and left to crystallize in a freezer to give N,N-dimethylaminoferrocene (11) (1.11 g, 91%) as orange flakes; mp 69-70° C. (hexanes); IR (KBr) vmax 3106, 2981, 2952, 2857, 2827, 2782, 1508 cm−1, 1H NMR (300 MHz, CDCl3) 4.25 (s, 5H), 3.93 (s, 2H), 3.78 (s, 2H), 2.59 (s, 6H); 13C NMR (75.5 MHz, acetone-d6) 115.8, 66.5, 63.0, 54.6, 41.5; EIMS [m/z(%)] 229 (M+, 100), 186 (18), 121 (17); HRMS (EI) calcd for C12H16N56Fe: 229.0554. Found 229.0553. Anal. Calcd for C12H16N56Fe: C, 62.91; H, 6.60. Found: C, 62.95; H, 6.60.

Workup

  1. extractionextracted with hexanes (3×20 mL)
  2. extractionThe combined organic extract
  3. washwas washed with water and brine
  4. dry with materialdried over anhydrous Na2SO4
  5. filtrationfiltered
  6. concentrationconcentrated to approx. 5% of its original volume under reduced pressure
  7. filtrationThe solution was filtered through basic alumina (20 mL) with hexanes
  8. concentrationconcentrated back to its pre-filtration volume
  9. waitleft
  10. customto crystallize in a freezer

Sources & evidence

ORD record
ord-d050e5b77a9f49da822f77296131abd1
Source dataset
uspto-grants-2011_07
Patent number
US07982064B2

Reaction notes

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