Trifluoroacetic Acid

Used Chemicals

• 1-Phenylpropargyl Alcohol [P0220]
• Hydrazine Monohydrate [H0172]
• Trifluoroacetic Acid (= TFA) [T0431]
• Methanol

Procedure

Trifluoroacetic acid (0.355 mL, 4.64 mmol, 11.6 eq.) was added to a solution of 1-Phenylpropargyl alcohol (52.9 mg, 0.40 mmol) and hydrazine monohydrate (500 mg, 10.0 mmol, 25 eq.) in methanol (5 mL) at room temperature. An RVC electrode was immersed in the solution and constant current electrolysis was performed at a current of 40 mA until an electrical flow of 45 F/mol was completed. Water (20 mL) was added to the reaction mixture and the aqueous layer was extracted with diethyl ether (20 mL, twice). The combined organic layer was dried over sodium sulfate and filtered. The solvent was removed under reduced pressure to give 1-phenyl-1-propanol as a colorless liquid (57.2 mg, >99% yield).

Experimenter’s Comments

The reaction mixture was monitored by UPLC.
The experiment was conducted in a fume hood because gas is produced during the reaction.
The reaction was carried out for about 8 hours.
IKA ElectraSyn 2.0 was used as an electrolytic apparatus in this experiment.

Analytical Data

1-phenyl-1-propanol

¹H NMR (400 MHz, CDCl₃); δ 7.39–7.26 (m, 5H), 4.59 (t, J = 6.4 Hz, 1H), 2.07 (br s, 1H), 1.88–1.70 (m, 2H), 0.92 (t, J = 7.2 Hz, 3H).

Lead Reference

• eHydrogenation: Hydrogen-free Electrochemical Hydrogenation
  • C. Russo, M. C. Leech, J. M. Walsh, J. I. Higham, L. Giannessi, E. Lambert, C. Kiaku, D. L. Poole, J. Mason, C. A. I. Goodall, P. Devo, M. Giustiniano, M. Radi, K. Lam, Angew. Chem, Int. Ed. 2023, 62, e202309563.

Reference

• Protection for the Hydroxyl Group, Including 1,2- and 1,3-Diols
  • P. G. M. Wuts, in Greene’s Protective Groups in Organic Synthesis, 5th ed., ed. by P. G. M. Wuts, John Wiley & Sons, Inc., Hoboken, New Jersey, 2014, Chap. 2, 17.

References

• Total syntheses of (+)-Altholactone [(+)-Goniothalenol] and three stereocongeners and their cytotoxicity against several tumor cell lines
  • Y. Ueno, K. Tadano, S. Ogawa, J. L. McLaughlin, A. Alkofahi, Bull. Chem. Soc. Jpn. 1989, 62, 2328.