2.5- dimethyl-N-substituted pyrrole

Ar= Ph, 2-MePh, 3-MjPh, 4-MePh, 4-MeOPh, 3-ClPh, 4-ClPli, 4-NO2PI1, CHjPh, 1-Naph SCHEME 3 Synthesis of 2,5-dimethyl-N-substituted pyrrole using [HMIM]HS04 as catalyst. 

Li et al. [44] reported a simple and efficient method for the preparation of 2,5-dimethyl-N-substituted pyrroles (9) using the ionic liquid [HM1MJHS04 as catalyst at 25-30 °C under ultrasonic irradiation (frequency of 40 kHz and a nominal power of 250W) (Scheme 3) the authors studied the effect of different cosolvents such as ethanol, methanol, and acetonitrile, and tiie best result was obtained with methanol (87% yield). This method has the advantages of reducing the response time and avoidance of toxic catalysts moreover, tiie catalyst was recovered and reused. 

Satyanarayana and Sivakumar [51] developed a simple, rapid, and efficient synthesis of 2,5-dimethyl-N-substituted pyrrole derivatives (15) by tiie Paal-Knorr reaction [45,46] by means of the one-pot condensation of 1,4-dicarbonyl compoxmds (13) and substituted primary amines (14) using uranyl nitrate hexahydrate as catalyst under ultrasonic irradiation (Scheme 5). The authors studied tiie reaction of methanol, ethanol, acetonitrile, dichlorometh-ane, or chloroform in solvents, as well as in the absence of solvent. The best yields were obtained with methanol under sonication for 5 min. 

V.S.V. Satyanarayana, A. Sivakumar, Ultrasound-assisted synthesis of 2,5-dimethyl-N-substituted pyrroles catalyzed by uranyl nitrate hexa-hydrate, Ultrason. Sonochem. 18 (2011) 917-922. 

---

See also in sourсe #XX -- [ ]

---