Syntheses of Calix[4]Pyrroles by Amberlyst-15 Catalyzed Cyclocondensations of Pyrrole with Selected Ketones

Abstract

A facile and efficient protocol is reported for the synthesis of calix [4]pyrroles and N-confused calix[4]pyrroles in moderate to excellent yields by reaction of dialkyl or cycloalkyl ketones with pyrrole catalyzed by reusable Amberlyst™-15 under eco-friendly conditions.

Synthesis of dipyrromethanes in aqueous media using boric acid

“…[16][17][18] Our research group has developed a few green methods for synthesis of dipyrromethanes and related compounds [19][20][21][22] in addition to other groups. [23][24][25] Boric acid has been used as catalyst for synthesis of bis(indolyl)methanes, 26 benzoxanthenes, 27 dehydration of glucose, 28 protection and deprotection of alcohols and ethers, 29 Nacylation, 30 bromination, 31 aza Michael reactions, 32 Biginelli reactions 33 and other condensation reactions.…”

Use of Graphite Oxide and Graphene Oxide as Catalysts in the Synthesis of Dipyrromethane and Calix[4]pyrrole

“…The reaction of 1 with 2a in the presence of Al-MCM-41 zeolite gave 3a and 4a in 12 and 70% yield, respectively [52]. The reaction of the above in the presence of Amberlyst TM -15 gave 4a and N-confused calix[4]pyrrole in 83 and 14% yield, respectively [55]. The high yield of 4a in acetone may be explained by initial formation of 3a which on subsequent reaction with acetone leads to calix[4]pyrrole.…”

“…They are synthesized by condensation of pyrroles with dialkylketones in the presence of aqueous acids [48,49], Lewis acids [50,51] and solid acids including zeolites [52], molecular sieves [53,54] and Amberlyst-15 [55] under different reaction conditions. Although various solid acids have been used in the synthesis of different calix[4]pyrroles, to the best of our knowledge graphite oxide and graphene oxides have not been used for this purpose.…”

Calix[n]pyrroles as Anion and Ion-Pair Complexants

“…Recent advances in the synthesis of this macrocycle include microwave-assisted synthesis of calix [4]pyrroles containing hydroxamic acids [26] and azo-functionalized derivatives [27]. Amberlyst TM -15 has been employed by Chauhan and co-workers as a solid acid catalyst, which can be removed from the reaction conveniently by filtration [28] whilst Kulkarni and co-workers have used molecular sieve MCM-41 as a heterogeneous catalyst for calixpyrrole synthesis [29]. Kumar and co-workers have used 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquids as a medium for ytterbium(III) triflate catalysed synthesis of calix [4]pyrroles, a method that works cleanly and in high yield for a variety of alkyl and aryl functionalized systems [30].…”