2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → Dimethyl 7-benzyloxy-3-(4-benzyloxyphenyl)-4-ethylpyrrolo[2,1,5-cd]indolizine-1,2-dicarboxylate

Participants

Reaction Steps

6-Benzyloxy-2-(4-benzyloxyphenyl)-1-ethylindolizine (50.0 g, 115 mmol) and dimethyl acetylene dicarboxylate (18.5 ml, 150 mmol) was dissolved in 1100 ml of dry toluene at 0° C. The reaction was slowly heated to room temperature and stirred for 3 hours. 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (26 g, 115 mmol) was added and stirring was continued for 1/2 hour. The mixture was filtered through celite and the solvent removed. The crude product was crystallised from methanol to afford 47.4 g (71%) of dimethyl 7-benzyloxy-3-(4-benzyloxyphenyl)-4-ethylpyrrolo[2,1,5-cd]indolizine-1,2-dicarboxylate as yellow crystals. M.p. 115-120° C. 1H-NMR (DMSO-d6, 300 MHz) δ: 1.32 (t, 3H); 3.01 (q, 2H); 3.56 (s, 3H); 3.72 (s, 3H); 5.21 (s, 2H); 5.50 (s, 2H); 7.17 (d, 2H; 7.32-7.53 (m, 10H); 7.60 (d, 2H); 7.67 (d, 1H); 8.22 (d, 1H).

Provenance & Evidence