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

Participants

Reaction Steps

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.

Provenance & Evidence