An efficient approach to 1,2,3-trisubstituted indole via rhodium catalyzed carbene C(sp(3))-H bond insertion.

A method for convenient synthesis of N-alkyl-2-aryl-indole-3-carbaldehyde has been described. A variety of highly valuable indolyl aldehydes have been prepared through this method. Electron donating groups on both aromatic rings (anilinyl and benzyl) facilitate the formation of the desired products. A benzylic C-H insertion by rhodium carbene is the key step for this transformation.

One-pot protocol to functionalized benzopyrrolizidine catalyzed successively by Rh2(OAc)4 and Cu(OTf)2: a transition metal-Lewis acid catalysis relay.

4-N-allylarylpropylamino-1-sulfonyl triazoles are converted to structurally unique benzopyrrolizidinyl sulfonamides in a one-pot operation. Intramolecular capture of rhodium carbene with arylamino nitrogen gives rise to the formation of an ammonium ylide immediate. A [2,3]- or [1,2]-rearrangement occurs to give a 2-allylpyrrolidinyl-2-carbimine intermediate which undergoes Cu(OTf)2 catalyzed aza-Friedel-Crafts cyclization to finish a highly functionalized tricyclic system decorated with a synthetically difficult quaternary carbon center, a sulfonamide group, and an allyl segment.

Copper-catalyzed cyclization/aza-Claisen rearrangement cascade initiated by ketenimine formation: an efficient stereocontrolled synthesis of α-allyl cyclic amidines.

An efficient and convenient synthesis of α-allyl cyclic amidines has been achieved by applying a novel cascade reaction. Copper(I)-mediated in situ N-sulfonyl ketenimine formation from the reaction of a terminal alkyne with sulfonyl azide is followed by an intramolecular nucleophilic attack on the central carbon atom by an allylic tertiary amine, and then an aza-Claisen rearrangement takes place through a chair transition state to furnish the titled amidines with complete stereocontrol.

Stereoselective halocyclization of alkenes with N-acyl hemiaminal nucleophiles.

Halocyclization of alkenes was realized using N-acylhemiaminal nucleophiles. High diastereoselectivity could be achieved for the formation of three stereogenic centers in this halogen-mediated cyclization reaction. We also demonstrated that enantioselective bromocyclization of alkenes using N-acylhemiaminal nucleophiles was possible.

Biocompatible and biodegradable polymer nanofibers displaying superparamagnetic properties.

Superparamagnetic polymer nanofibers intended for drug delivery and therapy are considered here. Magnetite (Fe3O4) nanoparticles in the diameter range of 5-10 nm were synthesized in aqueous solution. Polymer nanofibers containing magnetite nanoparticles were prepared from commercially available poly(hydroxyethyl methacrylate), PHEMA, and poly-L-lactide (PLLA) by the electrospinning technique. Nanofibers with diameters ranging from 50 to 300 nm were obtained. Nanofibers containing up to 35 wt % magnetite nanoparticles displayed superparamagnetism at room temperature. The blocking temperature was about 50 K for an applied field of 500 Oe, and the saturation magnetization was 3.5 emu g(-1) and 1.1 emu g(-1) for Fe3O4/PHEMA and Fe3O4/PLLA nanofibers, respectively, and depended on the amount of Fe3O4 nanoparticles in the nanocomposites. To test such magnetic nano-objects for applications as drug carriers and drug-release systems we incorporated a fluorescent albumin with dog fluorescein isothiocyanate (ADFI).