Zn(II)-Catalyzed Addition of Aromatic/Heteroaromatic C(sp<sup>2</sup>)–H to Azoalkenes: A Polarity-Reversed Arylation of Carbonyl Compounds
作者:Cecilia Ciccolini、Lucia De Crescentini、Fabio Mantellini、Stefania Santeusanio、Gianfranco Favi
DOI:10.1021/acs.orglett.9b01628
日期:2019.6.7
An umpolung α-(hetero)arylation strategy that involves the Michael-type reaction between electron-rich (hetero)aromatic substrates and azoalkenes is developed. The reaction proceeds under very mild conditions at room temperature and in the presence of inexpensive, nontoxic ZnCl2 catalyst to provide access to otherwise inaccessible hydrazone structures. Subsequent hydrolysis of these latter to ketones
Flexible Protocol for the Chemo- and Regioselective Building of Pyrroles and Pyrazoles by Reactions of Danishefsky’s Dienes with 1,2-Diaza-1,3-butadienes
作者:Orazio A. Attanasi、Gianfranco Favi、Paolino Filippone、Gianluca Giorgi、Fabio Mantellini、Giada Moscatelli、Domenico Spinelli
DOI:10.1021/ol800557h
日期:2008.5.1
The versatility of the Mukaiyama-Michael-type addition/heterocyclization of Danishefsky's diene with 1,2-diaza-1,3-butadienes was applied to the synthesis of both 4H-1-aminopyrroles and 4,5H-pyrazoles. Thus, the same reagents furnished different types of highly functionalized azaheterocycles essentially depending on their structure: as a matter of fact, R-1 = COOR or CONR2 differently affects the acidity of the proton at the adjacent carbon. An unexpected formation of 5H-1-aminopyrroles from the reactions carried out in water was also observed.
Lewis Acid-Catalyzed Synthesis of Functionalized Pyrroles
作者:Orazio A. Attanasi、Stefano Berretta、Lucia De Crescentini、Gianfranco Favi、Gianluca Giorgi、Fabio Mantellini
DOI:10.1002/adsc.200800807
日期:2009.3
Abstractmagnified imageThe synthesis of highly functionalized pyrroles is described. The sequence involves the preliminary preparation of α‐aminohydrazones by Michael addition of primary amines to 1,2‐diaza‐1,3‐butadienes. The treatment of these compounds with dialkyl acetylenedicarboxylates produces α‐(N‐enamino)‐hydrazones that were converted into the corresponding pyrroles by Lewis acid‐catalyzed ring closure. A screening of several Lewis/Brønsted acid catalysts was also performed.