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TCI Practical Example: Hosomi-Sakurai Allylation via an Imine Intermediate

We are proud to present the three component reaction with the Hosomi-Sakurai allylation reaction using allyl(trimethyl)silane.

Used Chemicals

• Cyclopentanone [C0510]
• Benzyl Carbamate [C0590]
• Allyl(trimethyl)silane [A0729]
• Boron Trifluoride - Ethyl Ether Complex (=BF₃·Et₂O) [B0527]
• Dichloromethane

Procedure

Cyclopentanone (890 µL, 10 mmol), benzyl carbamate (1.81 g, 12 mmol) and allyltrimethylsilane (2.2 mL, 14 mmol) were dissolved in dichloromethane (14 mL). After cooling to 0 °C, BF₃·Et₂O (1.51 mL, 12 mmol) was added and the reaction mixture was stirred for 21 hours at room temperature. After the reaction, the mixture was washed with satd. NaHCO₃ aq. (10 mL), brine (20 mL), dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (hexane:ethyl acetate = 9:1) to afford benzyl (1-allylcyclopentyl)carbamate (1.84 g, 71% yield) as a clear yellow liquid.

Experimenter’s Comments

The reaction solution was monitored by UPLC.

Analytical Data

Benzyl (1-Allylcyclopentyl)carbamate

¹H NMR (400 MHz, CDCl₃); δ 7.35-7.29 (m, 5H), 5.82-5.72 (m, 1H), 5.06-5.02 (m, 4H), 4.68 (brs, 1H), 2.52-2.51 (m, 2H), 1.76-1.61 (m, 8H).

Other References

• Scalable Synthesis of Biologically Relevant Spirocyclic Pyrrolidines
• • K. P. Melnykov, A. N. Artemenko, B. O. Ivanenko, Y. M. Sokolenko, P. S. Nosik, E. N. Ostapchuk, O. O. Grygorenko, D. M. Volochnyuk, S. V. Ryabukhin, ACS Omega 2019, 4, 7498.