SD Super Fine™ (Sodium 25wt% dispersion in mineral oil)

Used Chemicals

• Decylbenzene [D0034]
• SD Super Fine™ (Sodium 25wt% dispersion in mineral oil) [D5792]
• 1,3-Dimethyl-2-imidazolidinone [D1477]
• tert-Butyl Alcohol [B0706]
• Tetrahydrofuran

Procedure

To reaction vessel under nitrogen atmosphere, 1,3-dimethyl-2-imidazolidinone (5.0 mL), tetrahydrofuran (0.42 mL)　were added successively and cooled in ice bath. And SD Super Fine™ (Sodium 25wt% dispersion in mineral oil, 0.70 g) weighted in a syringe was added to the mixture. Decylbenzene (0.42 g, 1.9 mmol) and tert-butyl alcohol (0.57 g, 7.7 mmol)　were added at the same temperature. After 30 minutes, confirmed consumption of raw material completely by TLC, the reaction mixture was added to ice water. The aqueous layer was extracted with hexane and the organic layer was washed with brine and dried over magnesium sulfate. After filtration, the filtrate was concentrated. The obtained crude product was purified by silica gel column chromatography (hexane) and 1-decyl-1,4-cyclohexadiene (388 mg, yield 92% (NMR), containing 13% 1-decylcyclohex-1-ene) as a colorless oil.

Experimenter’s Comments

The reaction mixture was monitored by TLC (hexane, Rf = 0.9).
Since this reaction does not require liquid ammonia, it is more convenient to perform than the conventional Birch reduction.

Lead Reference

• Birch Reduction of Arenes Using Sodium Dispersion and DMI under Mild Conditions
• S. Asako, I. Takahashi, T. Kurogi, Y. Murakami, L. Ilies, K. Takai, Chem. Lett. 2022, 51, 38.

Other Reference

• A Practical and Chemoselective Ammonia-Free Birch Reduction
• P. Lei, Y. Ding, X. Zhang, A. Adijiang, H. Li, Y. Ling, J. An, Org. Lett. 2018, 20, 13439.

References

• Organosodium Compounds for Catalytic Cross-coupling
  • S. Asako, H. Nakajima, K. Takai, Nat. Catal. 2019, 2, 297.