tert-butyl (1S)-1-[(4-benzyl-2-vinyl-1-piperazinyl)carbonyl]-3-butenylcarbamate → tert-butyl (7S)-2-benzyl-6-oxo-1,2,3,4,6,7,8,10a-octahydropyrazino[1,2-a]azepin-7-ylcarbamate

Participants

Reaction Steps

tert-Butyl (1S)-1-[(4-benzyl-2-vinyl-1-piperazinyl)carbonyl]-3-butenylcarbamate (250 mg, 0.63 mmol) and Grubb's catalyst (26 mg, 0.03 mmol) were combined in toluene (32 mL) at room temperature. This mixture was degassed via vacuum-argon three times at room temperature. Then CH2Cl2 (32 mL) was added in one portion. The reaction mixture was heated at reflux for 5 days, then concentrated in vacuo. The residue was purified by SGC (4:1 hex-EtOAc) to give the title product (103 mg, 44%) as a yellow powder. The 1H NMR spectrum was consistent with the presence of one diastereomer, not assigned. (300 MHz, CDCl3) δ 7.35-7.27 (m, 5H), 5.76-5.72 (m, 2H), 5.67-5.58 (m, 1H), 5.35-5.01 (m, 1H), 4.68 (br s, 1H), 4.00 (m, 1H), 3.64 (d, 1H, J=13.1 Hz), 3.42 (d, 1H, J=13.2 Hz), 3.09 (dt, 1H, J=13.5, 4.1 Hz), 2.91-2.86 (m, 1H), 2.76-2.72 (m, 2H), 2.26-2.00 (m, 3H), 1.44 (s, 9H) ppm.

Provenance & Evidence