Lawesson's reagent → (6S)-1-(2-chloro-3-(trifluoromethyl)benzyl)-6-ethyl-3-thioxopiperazin-2-one

Participants

Reaction Conditions

Reaction Steps

To a heterogeneous mixture of Lawesson's reagent (346 mg, 0.83 mmol) in THF (16 mL) was added (6S)-1-(2-chloro-3-(trifluoromethyl)benzyl)-6-ethylpiperazine-2,3-dione (555 mg, 1.7 mmol) at once. The mixture was heated at 55° C. for 20 minutes and then concentrated to remove the solvent. Purification by chromatography (SiO2; hexanes—100% EtOAc) afforded the desired product as a yellow oil (528 mg, 91%). MS (ESI): mass calcd. for C14H14ClF3N2OS, 350.1; m/z found, 335.1 [M+H]+. 1H NMR (400 MHz, CDCl3) δ 8.99 (s, 1H), 7.69 (dd, J=15.9, 7.8 Hz, 2H), 7.38 (t, J=7.8 Hz, 1H), 5.24 (d, J=15.3 Hz, 1H), 4.50 (d, J=15.3 Hz, 1H), 3.67 (dd, J=13.7, 3.9 Hz, 1H), 3.45 (dd, J=12.8, 5.4 Hz, 2H), 1.91-1.75 (m, 2H), 1.00 (t, J=7.5 Hz, 3H).

Provenance & Evidence