Search

Metal-free and environmentally friendly synthesis highly controlled by natural sources like visible light and air (or oxygen) is always a pursuit of green chemistry. In this paper, an atmosphere and light tuned highly diastereoselective synthesis of two important polyheterocyclic skeletons: cyclobuta/penta[b]indoles from aniline-tethered alkylidenecyclopropanes with alkynes, has been developed. The chiral cyclobuta/penta[b]indoles have also been obtained by optical resolution. [ABSTRACT FROM AUTHOR]

A Cu-catalyzed regio- and enantioselective aminoboration of alkylidenecyclopropanes (ACPs) with bis(pinacolato)-diboron (B2pin2) and hydroxylamines has been described in this paper, affording the corresponding cyclopropane-containing β-aminoalkylboranes in good yields under mild conditions. Moreover, a catalytic asymmetric variant of this transformation has also been realized by using a copper complex with a (S)-BINAP ligand along with further transformation of the product to give cyclopropane-containing 1,2-aminoalcohols. [ABSTRACT FROM AUTHOR]

The PdCl2-promoted reactions of methylenecyclopropanes (MCPs) 1bearing diaryl substituents on the terminal double bond were carefully investigated. The solvents employed significantly affected the reaction outcomes. It was found that dimeric allylpalladium(ii) complexes 2a–2fcan be obtained as the sole products in acceptable to good yields under mild reaction conditions with THF as the solvent, while dimeric allylpalladium(ii) complexes 2a–2falong with another type of dimeric allylpalladium(ii) complexes 4a–4ecan be obtained in good to high total yields if N,N-dimethylacetamide (DMAc) was used as the solvent. Moreover, using N,N-dimethylformamide (DMF) as the solvent in the presence of water, it was found that water can also participate in the reaction to form another type of dimeric allylpalladium(ii) complex 6as the minor product. All of these dimeric allylpalladium(ii) complexes reported in the paper have been characterized by X-ray crystal structure diffraction. [ABSTRACT FROM AUTHOR]

A catalyst-free intramolecular geminal aminofluorination of ortho-sulfonamide-tethered alkylidenecyclopropanes has been developed. The reaction proceeded through two SET processes with Selectfluor to give a fluorinated cyclopropylcarbinyl cation and a further Wagner-Meerwein rearrangement to generate a cyclobutyl carbocation, which undergoes intramolecular nucleophilic capture by amide to forge fluorinated cyclobuta[b]indoline derivatives. A polycyclic multi-fluorinated byproduct was also formed through a Ritter-type reaction in some cases. [ABSTRACT FROM AUTHOR]

The gold(i)-catalyzed dehydrogenative cycloisomerization of cyclopropane-tethered 1,5-enynes proceeded smoothly to give multisubstituted benzene derivatives in good to excellent yields. Synthetically important benzocyclobutenes can be produced in high yields in the presence of a gold(i) catalyst and DDQ. Furthermore, this reaction also works very well for non-cyclopropane tethered 1,5-enynes. [ABSTRACT FROM AUTHOR]

The unprecedented palladium-catalyzed cascade cyclization of allylamine-tethered alkylidenecyclopropanes with an ethyl difluoroiodoacetate or perfluoroalkylated reagent is developed, providing facile access to a variety of synthetically and medicinally valuable iodine/difluoromethylene- and perfluoroalkyl-containing 1-benzazepine frameworks. These reactions exhibited good yields and functional group tolerance via a radical mechanism. [ABSTRACT FROM AUTHOR]

We have developed a facile synthetic method to access furoquinoline and thienoquinoline derivatives via a thermally induced ring-opening and cyclization reaction from ortho-aminoaryl-tethered alkylidenecyclopropanes with the in situ generation of isocyanates or isothiocyanates. These reactions exhibited excellent yields and functional group tolerance under metal-free conditions. [ABSTRACT FROM AUTHOR]