Recent advances in ring-forming reactions of donor–acceptor cyclopropanes

Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals

A cooperative catalytic strategy of chiral iminium catalysis by regioselective activation of the C=C bond in enals and a transition metal promoting to open the 2-vinylcyclopropanes for highly regio- and enantioselective [3 + 2] cycloaddition reaction of 2-vinylcyclopropanes with α,β-unsaturated aldehydes has been developed.

Nickel(ii)-catalyzed enantioselective cyclopropanation of 3-alkenyl-oxindoles with phenyliodonium ylide via free carbene

A chiral Lewis acid-promoted cyclopropanation using a phenyliodonium ylide as the carbene precursor was developed. An EPR spectroscopy study supported a stepwise biradical mechanism.

A chiral Lewis acid-promoted enantioselective cyclopropanation using phenyliodonium ylide as the carbene precursor was developed. A variety of spirocyclopropane-oxindoles with contiguous tertiary and all carbon quaternary centers were obtained in excellent outcomes (up to 99% yield, >19 : 1 d.r., up to 99% ee). EPR spectroscopy study supported a stepwise biradical mechanism.

Synthesis and reactivity of alkoxy-activated cyclobutane-1,1-dicarboxylates

Donor–acceptor (DA) cyclopropanes are extensively studied and well established as building blocks for the synthesis of highly substituted carbo- and heterocyclic compounds. Despite of similar ring strain, the homologous DA cyclobutanes were long ignored. This personal account details our group's research towards the application of DA cyclobutanes in cycloaddition chemistry.

One-Pot Synthesis of Esters of Cyclopropane Carboxylic Acids via Tandem Vicarious Nucleophilic Substitution-Michael Addition Process

α-Chlorocarbanions generated via base-induced vicarious nucleophilic substitution reaction of alkyl dichloroacetates with nitroarenes react with Michael acceptors to give esters of cyclopropane carboxylic acids substituted with p-nitroaromatic rings.

Carbocycles from donor–acceptor cyclopropanes

Donor–acceptor cyclopropane annulations – not just for heterocycles.

Efficient strategy for construction of 6-carbamoylfulvene-6-carboxylate skeletons via [3 + 2] cycloaddition of 1-cyanocyclopropane 1-ester with β-nitrostyrenes

An efficient and straightforward the preparation of 6-carbamoylfulvene-6-carboxylates via a cycloaddition reaction between 1-cyanocyclopropane 1-ester and β-nitrostyrenes.

Synthesis of 2,3-disubstituted thiophenes from 2-aryl-3-nitro-cyclopropane-1,1-dicarboxylates and 1,4-dithiane-2,5-diol

A two-step synthesis of 2,3-disubstituted thiophenes from trans-2-aryl-3-nitrocyclopropane-1,1-dicarboxylates and 1,4-dithiane-2,5-diol is described.

Stereoselective synthesis of medicinally relevant furo[2,3-d]pyrimidine framework by thermal rearrangement of spirocyclic barbiturates

The thermally initiated transformation of substituted spirocyclic barbiturates in DMSO at 100 °C results in the stereoselective formation of medicinally relevant furo[2,3-d]pyrimidines in 50–75% yields.

Lewis acid catalyzed intramolecular [3 + 2] cross cycloadditions of cobalt-alkynylcyclopropane 1,1-diesters with carbonyls for construction of medium-sized and polycyclic skeletons

A Lewis acid catalyzed intramolecular [3 + 2] cross cycloaddition of cobalt-alkynylcyclopropane 1,1-diesters with carbonyls has been successfully developed. Together with simple and efficient postcycloadditions of the cobalt-alkyne moiety, a general and efficient strategy for construction of structurally complex and diverse medium-sized skeletons and related polycycles was supplied successfully.