DBU-promoted ring-opening reactions of multi-substituted donor–acceptor cyclopropanes: access to functionalized chalcones with a quaternary carbon group

A strategy to synthesize highly stereoselective chalcones with alkylcyanoacetate subunits via DBU-promoted ring-opening reactions of multi-substituted D–A cyclopropanes has been developed without the requirement of a transition metal catalyst and extra solvent.

Direct synthesis of highly functionalized furans from donor-acceptor cyclopropanes via DBU-mediated ring expansion reactions

A DBU-mediated, unprecedented formal ring expansion reaction of 2-acyl-3-arylcyclopropane-1,1-dicarbonitriles for the synthesis of multisubstituted furan derivatives is reported. This transformation represents the regioselective ring-opening reaction of cyclopropane-1,1-dicarbonitriles and annulation using an intramolecular addition cascade reaction protocol for the synthesis of fully substituted furans includes use of readily available starting materials, mild reaction conditions, and it is transition-metal catalyst free, has good functional tolerance, and broad substrate scope.

DBU-Mediated Cyclization of Acylcyclopropanecarboxylates with Amidines: Access to Polysubstituted Pyrimidines

DBU-mediated cyclization of 2-acyl-1-cyanocyclopropanecarboxylates with amidines for the synthesis of multisubstituted pyrimidine derivatives is described. This reaction gives a practical method for producing a diverse set of pyrimidines, having simple experimentation, readily available starting materials, a wide substrate scope, and very good yields.

Novel synthesis of highly functionalized cyclopentane derivatives via [3 + 2] cycloaddition reactions of donor–acceptor cyclopropanes and (E)-3-aryl-2-cyanoacrylates

An efficient [3 + 2] cycloaddition reaction of cyanocyclopropanecarbonates and ( E)-3-aryl-2-cyanoacrylates mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene for the synthesis of highly functionalized cyclopentane derivatives in moderate to good yields (79%−87%) was developed. The structures of two typical products were confirmed by X-ray crystallography.

DBU-mediated [4 + 2] annulations of donor–acceptor cyclopropanes with 3-aryl-2-cyanoacrylates for the synthesis of fully substituted anilines

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.

DBU-mediated [4 + 1] annulations of donor–acceptor cyclopropanes with carbon disulfide or thiourea for synthesis of 2-aminothiophene-3-carboxylates

Fully substituted 2-aminothiophene-3-carboxylate derivatives were synthesized effectivelyviathe DBU-mediated [4 + 1] annulations of donor–acceptor cyclopropanes with carbon disulfide or thiourea.

Brönsted acid-mediated annulations of 1-cyanocyclopropane-1-carboxylates with arylhydrazines: efficient strategy for the synthesis of 1,3,5-trisubstituted pyrazoles

A diversity-oriented synthesis of 1H-pyrazole derivatives via Brönsted acid-promoted annulations of 1-cyanocyclopropane-1-carboxylates with arylhydrazines has been developed.