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TCI Practical Example: Di-Boc Guanidinylation of Amine Using the Guanidinylating Agent

We are proud to present the di-Boc guanidinylation of 4-bromophenethylamine using 1-[N,N'-(di-Boc)amidino]pyrazole as a guanidinylating agent.

Used Chemicals

• 4-Bromophenethylamine [B3454]
• 1-[N,N'-(Di-Boc)amidino]pyrazole [B3619]
• THF

Procedure

A solution of 4-bromophenethylamine (200 mg, 1.00 mmol) and 1-[N,N'-(di-Boc)amidino]pyrazole (341 mg, 1.10 mmol) in THF (1.7 mL) was stirred at room temperature for one day. The reaction mixture was concentrated under reduced pressure and the residue was purified by column chromatography (on silica gel, ethyl acetate:hexane = 0:100 - 10:90) to give the guanidinylated compound 1 as a pale yellow solid (319 mg, 72% yield.).

Experimenter's Comments

The reaction mixture was monitored by TLC (ethyl acetate:hexane = 1:3, Rf = 0.55).

Analytical Data

Guanidinylated Compound 1

¹H NMR (270 MHz, DMSO-d₆); δ 11.48 (s, 1H), 8.32 (t, J = 6.4 Hz, 1H), 7.48 (d, J = 8.1 Hz, 2H), 7.15 (d, J = 8.1 Hz, 2H), 3.51 (q, J = 6.4 Hz, 2H), 2.78 (t, J = 6.4 Hz, 2H), 1.47 (s, 9H), 1.40 (s, 9H)

Lead Reference

• Urethane protected derivatives of 1-guanylpyrazole for the mild and efficient preparation of guanidines
  • M. S. Bernatowicz, Y. Wu, G. R. Matsueda, Tetrahedron Lett. 1993, 34, 3389.