Reaction Steps
A mixture of Cs2CO3 (115 mg, 0.354 mmol), acetylacetone (12 μL, 0.12 mmol), CuCl (5.8 mg, 0.059 mmol) and THF (2.5 mL) in a vial was stirred at room temperature for 5 min before (4-hydroxy-3-methoxy-phenyl)-[2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-yl]methanone (100 mg, 0.236 mmol) then 2-bromoprop-1-ene (27 μL, 0.31 mmol) were added. The vial was capped and heated at 70° C. overnight. The mixture was cooled to room temperature, filtered and concentrated under reduced pressure. The residue was subjected to column chromatography (0-100% ethyl acetate/hexanes) to give (4-isopropenyloxy-3-methoxy-phenyl)-[2-methyl-6-(trifluoromethyl)spiro[3,4-dihydropyrrolo[1,2-a]pyrazine-1,4′-piperidine]-1′-yl]methanone (8.9 mg, 8%). ESI-MS m/z calc. 463.2, found 464.3 (M+1)+; Retention time: 1.47 minutes (3 min run). 1H NMR (400 MHz, CD3CN) δ 7.12 (d, J=1.8 Hz, 1H), 7.07 (d, J=8.0 Hz, 1H), 7.01 (dd, J=8.0, 1.8 Hz, 1H), 6.60 (d, J=3.4 Hz, 1H), 6.07 (d, J=3.7 Hz, 1H), 4.42 (s, 1H), 4.12 (dd, J=1.6, 0.9 Hz, 1H), 4.01 (t, J=6.0 Hz, 2H), 3.85 (s, 3H), 3.79 (d, J=1.7 Hz, 1H), 3.67-3.40 (m, 2H), 3.36 (t, J=5.6 Hz, 2H), 3.20 (s, 1H), 2.36 (s, 3H), 2.18 (s, 2H), 2.00 (d, J=0.7 Hz, 3H), 1.83 (s, 2H).
