Microwave‐Accelerated Synthesis of Benzyl 3,5‐Dimethyl‐pyrrole‐2‐carboxylate.

Abstract

Pyrrole derivatives R 0120Microwave-Accelerated Synthesis of Benzyl 3,5-Dimethyl-pyrrole-2-carboxylate.-Microwave irradiation is used to accelerate transesterification and deacetylation reaction, resp., to the title compound (III). The optimization of the reaction conditions is discussed. -(REGOURD, J.; COMEAU, I. M.; BESHARA, C. S.; THOMPSON*, A.; J. Heterocycl. Chem. 43 (2006) 6, 1709-1714; Dep. Chem., Dalhousie Univ., Halifax, Nova Scotia B3H 4J3, Can.; Eng.) -H. Haber

Synthesis and Anti-Cancer Activity of C-Ring-Functionalized Prodigiosin Analogues

“…Diesters 21-23 were mono-saponified, and the resultant mono-acids were chlorinated 42 to give the chlorocarbonyl esters 27-29. Subsequent Friedel-Crafts acylation of benzyl 3,5dimethyl-pyrrole-2-carboxylate 43 gave the pyrroles 30-32, which were hydrogenolyzed, and the resultant carboxylic acids (33)(34)(35) were decarboxylated by treatment with TFA. 44 Finally, in-situ Vilsmeier-Haack formylation 40 gave the formyl pyrroles 36-38.…”

“…4-(3-Ethoxycarbonyl-propanoyl)-3,5-dimethyl-1H-pyrrole-2carboxylic Acid Benzyl Ester (30). Benzyl 3,5-dimethyl-pyrrole-2-carboxylate 43 (9.98 g, 43.62 mmol) was dissolved in degassed CH 2 Cl 2 (75 mL) and stirred for 15 min at 0 °C under N 2 . SnCl 4 (6.1 mL, 52.12 mmol) was added dropwise, and the reaction mixture was stirred at 0 °C for a further 10 min, after which 27 (7.10 g, 43.62 mol) in anhydrous dichloromethane (20 mL) was slowly added.…”

“…Following the procedure as for the synthesis of 36, the title compound was obtained as a white solid (30%); mp ) 69 °C; R f 0.56 (50:50 ethyl acetate:hexane); δ H (500 MHz, CDCl 3 ) 9.80 (1H, bs), 9.68 (1H, s), 4.16 (2H, q, J 7.1), 2.76 (2H, t, J 7.3), 2.61 (3H, s), 2.60 (3H, s), 2.32 (2H, t, J 7.5), 1.74-1.64 (4H, m), 1.39-1.31 (8H, m), 1.29 (3H, t, J 7.1); δ C (125 MHz, CDCl 3 ) 197.8, 177.5, 173.9, 142.0, 133.6, 128.2, 123.7, 60.2, 42.9, 34. (43). Purged KOH (4 M, 4 mL, 16.00 mmol) was added dropwise to a purged solution of 4-methoxy-3-pyrrolin-2-one (1.36 g, 12.00 mmol) in THF (80 mL), and the reaction mixture was stirred at 60 °C for 1 h under N 2 , after which 36 (2.01 g, 8.00 mmol) was added.…”