title: Stereoselective Synthesis of Lower and Upper Rim Functionalized Tetra-α Isomers of Calix[4]pyrroles.
abstract: Hydroxyaryl alkyl ketones with functionalized alkyl chains often fail to produce the corresponding tetra-α calix[4]pyrroles in Brönsted acid mediated condensations with pyrrole. A remarkable effect exerted by the addition of methyltrialkylammonium chloride during the acid-mediated syntheses of a series of meso-(tetrahydroxyaryl)-meso-tetraalkylcalix[4]pyrroles featuring alkyl terminal chloro or ester groups is reported. The ammonium salt enhances the cyclocondensation reaction and induces the almost exclusive formation of the tetra-α isomers.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST) , Avda. Països Catalans 16, 43007 Tarragona, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Díaz-Moscoso
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST) , Avda. Països Catalans 16, 43007 Tarragona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hernández-Alonso
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST) , Avda. Països Catalans 16, 43007 Tarragona, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Escobar
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST) , Avda. Països Catalans 16, 43007 Tarragona, Spain.
authors.forename: Frank A
authors.initials: FA
authors.lastname: Arroyave
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST) , Avda. Països Catalans 16, 43007 Tarragona, Spain.|ICREA , Passeig Lluís Companys 23, 08010 Barcelona, Spain.
authors.forename: Pablo
authors.identifier: 0000-0001-8377-6610
authors.initials: P
authors.lastname: Ballester