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TCI Practical Example: Diborylation of Alkynes with a Platinum Catalyst

We are proud to introduce the diborylation reaction to diphenylacetylene using Pt(PPh₃)₄ catalyst.

Used Chemicals

• Tetrakis(triphenylphosphine)platinum(0) (= Pt(PPh₃)₄) [T2485]
• Diphenylacetylene [D0871]
• Bis(pinacolato)diboron [B1964]
• DMF
• Toluene

Procedure

To a degassed solution of diphenylacetylene (100 mg, 0.561 mmol) and bis(pinacolato)diboron (144 mg, 0.567 mmol) in DMF (0.5 mL) and toluene (0.5 mL) was added Pt(PPh₃)₄ (2 mg, 0.25 mol%). The reaction mixture was heated to 80 °C for 24 hours. After this time, the reaction was diluted with toluene (10 mL) and washed with saturated aqueous NH₄Cl (2 x 10 mL). The organic phase was dried over MgSO₄ and concentrated under reduced pressure. Recrystallization from methanol afforded 1 as a white solid (241 mg, 0.558 mmol, 99%).

Experimenter’s Comments

The reaction mixture was monitored by TLC (CH₂Cl₂:hexane = 2:1, Rf = 0.45).

Analytical Data

Compound 1

¹H NMR (400 MHz, CDCl₃); δ 7.02-7.09 (m, 6H), 6.94-6.96 (m, 4H), 1.32 (s, 24H).

¹³C NMR (101 MHz, CDCl₃); δ 141.3, 129.3, 127.4, 125.8, 84.1, 24.9.

Lead Reference

• Platinum(0)-catalyzed diboration of alkynes
• T. Ishiyama, N. Matsuda, N. Miyaura, A. Suzuki, J. Am. Chem. Soc. 1993, 115, 11018.

Other References

• Divergent and Stereoselective Synthesis of Tetraarylethylenes from Vinylboronates
• M. Zhang, Y. Yao, P. J. Stang, W. Zhao, Angew. Chem. Int. Ed. 2020, 59, 20090.