Pyrrole and oligopyrrole synthesis by 1,3-dipolar cycloaddition of azomethine ylides with sulfonyl dipolarophiles.
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).
Robles-Machín
Rocío
R
Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain.
López-Pérez
Ana
A
González-Esguevillas
María
M
Adrio
Javier
J
Carretero
Juan Carlos
JC
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*
D001391:Azo Compounds; D011758:Pyrroles; D013450:Sulfones; D013882:Thiosemicarbazones; C512188:azomethine