title: Pyrrole and oligopyrrole synthesis by 1,3-dipolar cycloaddition of azomethine ylides with sulfonyl dipolarophiles.
abstract: A procedure for the synthesis of functionalized, substituted pyrroles by 1,3-dipolar cycloaddition of azomethine ylides has been developed. This protocol is based on the metal-catalyzed cycloaddition of alpha-iminoesters with sulfonyl dipolarophiles, followed by the base-promoted elimination of the sulfonyl groups. A wide variety of 2,5-disubstituted and 2,3,5- and 2,4,5-trisubstituted pyrroles have been prepared in satisfactory yields from 1,2-bis(sulfonyl ethylene), beta-sulfonylenones, and beta-sulfonylacrylates. This method can be applied in an iterative and straightforward manner to the construction of oligopyrroles, from bipyrroles to pentapyrroles. Iterative [n+1] and [n+2] approaches have been devised, the latter involves double 1,3-dipolar cycloaddition from pyrrolyl-based bis(iminoesters).
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Robles-Machín
authors.forename: Ana
authors.initials: A
authors.lastname: López-Pérez
authors.forename: María
authors.initials: M
authors.lastname: González-Esguevillas
authors.forename: Javier
authors.initials: J
authors.lastname: Adrio
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Carretero
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D003500:Cyclization; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013450:Sulfones / Q000737:chemistry*; D013882:Thiosemicarbazones / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D011758:Pyrroles; D013450:Sulfones; D013882:Thiosemicarbazones; C512188:azomethine