An efficient one‐pot synthesis of highly substituted pyrroles from donor–acceptor cyclopropanes, salicylaldehydes, and ammonium acetate has been developed. This reaction involves a domino sequence involving the ring‐opening of donor–acceptor cyclopropanes, [3+2] annulation, and aromatization as the key steps. This elegant methodology readily afforded functionalized pyrroles under mild reaction conditions and with a wide substrate scope.
The diversity-oriented synthesis of fully substituted aniline derivatives via the DBU-mediated [4 + 2] annulation of donor-acceptor 1,1-dicyanocyclopropanes with 3-aryl-2-cyanoacrylate has been developed.
Multisubstituted furan derivatives were synthesized effectively using the DBU-mediated, unprecedented formal ring expansion reactions of 2-acyl-3-arylcyclopropane-1,1-dicarbonitriles.
DBU-mediated [4 + 1] annulations of donor-acceptor cyclopropanes with carbon disulfide or thiourea to form 2-aminothiophene-3-carboxylate derivatives have been discovered. This reaction proceeds via the ring opening of donor-acceptor cyclopropanes to produce a 2-(iminomethylene)but-3-enoate intermediate, followed by the attack of an S-nucleophile for regioselective intermolecular nucleophilic addition, intramolecular S-nucleophilic addition, and final aromatization. A variety of functional groups could be tolerated under the reaction conditions.
An atom-economical protocol to construct densely substituted
4-acyl-2-quinolones
from N-(2-alkynylphenyl)-α-ketoamides has been
developed through Sc(OTf)3-catalyzed ring-closing alkyne–carbonyl
metathesis. Mechanistic experimental studies support that coordinative
interaction between Sc(OTf))3 and the substrate, the formation
of an oxetene intermediate, and an electrocyclic ring-opening of the
oxetene might be involved.
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