TY - JOUR
T1 - Cascade synthesis of indolizines and pyrrolo[1,2-a]pyrazines from 2-formyl-1-propargylpyrroles
AU - Escalante, Carlos H.
AU - Carmona-Hernández, Fernando A.
AU - Hernández-López, Alberto
AU - Martínez-Mora, Eder I.
AU - Delgado, Francisco
AU - Tamariz, Joaquín
N1 - Publisher Copyright:
This journal is © The Royal Society of Chemistry
PY - 2022/1/14
Y1 - 2022/1/14
N2 - A straightforward synthesis of indolizines and pyrrolo[1,2-a]pyrazines was performed through a cascade condensation/cyclization/aromatization reaction of substituted 2-formyl-N-propargylpyrroles with active methylene compounds such as nitromethane, alkyl malonates, methyl cyanoacetate and malononitrile. Under basic conditions, the reaction proceeded satisfactorily to provide the corresponding 6,7-disubstituted indolizines. The condensation of the pyrrolic analogues with ammonium acetate gave rise to pyrrolo[1,2-a]pyrazines in high yields. N-Allenyl-2-formylpyrroles behaved as more reactive substrates than 2-formyl-N-propargylpyrroles, furnishing the expected indolizines in higher yields. Hence, an allenyl-containing intermediate was probably generated as the reactive species in the reaction mechanism of some N-propargyl pyrroles prior to the cyclization reaction.
AB - A straightforward synthesis of indolizines and pyrrolo[1,2-a]pyrazines was performed through a cascade condensation/cyclization/aromatization reaction of substituted 2-formyl-N-propargylpyrroles with active methylene compounds such as nitromethane, alkyl malonates, methyl cyanoacetate and malononitrile. Under basic conditions, the reaction proceeded satisfactorily to provide the corresponding 6,7-disubstituted indolizines. The condensation of the pyrrolic analogues with ammonium acetate gave rise to pyrrolo[1,2-a]pyrazines in high yields. N-Allenyl-2-formylpyrroles behaved as more reactive substrates than 2-formyl-N-propargylpyrroles, furnishing the expected indolizines in higher yields. Hence, an allenyl-containing intermediate was probably generated as the reactive species in the reaction mechanism of some N-propargyl pyrroles prior to the cyclization reaction.
UR - http://www.scopus.com/inward/record.url?scp=85122813184&partnerID=8YFLogxK
U2 - 10.1039/d1ob01839f
DO - 10.1039/d1ob01839f
M3 - Artículo
C2 - 34904608
AN - SCOPUS:85122813184
SN - 1477-0520
VL - 20
SP - 396
EP - 409
JO - Organic and Biomolecular Chemistry
JF - Organic and Biomolecular Chemistry
IS - 2
ER -