Catalyzed Cascade Reaction Research Articles

ChemInform Abstract: NiCl2‐Catalyzed Cascade Reaction of Isocyanides with Functionalized Anilines.

Abstract A NiCl 2 -catalyzed isocyanide insertion reaction of anilines bearing another nucleophile functional group utilizing TEMPO as oxidant in isopropyl ethanoate (IPA) or THF has been reported. This simple and general method could afford 2-aminobenzimidazole, 2-aminobenzothiazole, 2-aminobenzoxazole, as well as 2-aminobenzo[ d ][1,3]oxazine in moderate to excellent yields (up to 95% yield).

A Sc(OTf)3-catalyzed cascade reaction of o-aminoacetophenone with methanamine: construction of dibenzo[b,h][1,6]naphthyridine derivatives.

An unexpected Sc(OTf)3-catalyzed and air-mediated cascade reaction of o-aminoacetophenones with methanamines was discovered as an efficient synthetic approach to a novel class of fluorescent fused-four-ring dibenzo[b,h][1,6]naphthyridine derivatives. Two possible mechanisms of the reaction were proposed. The photophysical properties of the dibenzo[b,h][1,6]naphthyridine were initially considered.

ChemInform Abstract: Lewis Acid Catalyzed Cascade Reaction to Carbazoles and Naphthalenes via Dehydrative [3 + 3]‐Annulation.

AbstractThis novel reaction proceeds through a cascade process involving the cleavage and formation of multiple chemical bonds in a single operation releasing water as the only by‐product with readily available electron‐rich benzylic alcohols and propargylic alcohols as starting materials.

Heteroarylidene-tethered bis(oxazoline) copper complexes catalyzed cascade reaction involving asymmetric Friedel–Crafts alkylation/N-hemiacetalization of indoles with β,γ-unsaturated α-ketoester

A convenient approach to the synthetically and biologically useful indole derivatives was developed. A cascade sequence involving Friedel–Crafts alkylation of 3-methyl indoles with β,γ-unsaturated α-ketoester followed by N-hemiacetalization were realized using heteroarylidene-tethered bis(oxazoline)-copper complexes. The pyrroloindole products with two chiral centers were obtained in high yields (85–95%) with both high diastereoselectivities (87:13–96:4 drs) and enantioselectivities (87–98% ees). A plausible mechanism was proposed.

Construction of 3-(picolinoyl)indolizines: Rh(III)-catalyzed cascade reactions of 2-vinylpyridines.

Construction of 3-(picolinoyl)indolizines: Rh(III)-catalyzed cascade reactions of 2-vinylpyridines.

ChemInform Abstract: Three‐Component Pd/Cu‐Catalyzed Cascade Reactions of Cyclic Iodoniums, Alkynes, and Boronic Acids: An Approach to Methylidenefluorenes.

Linear diaryliodonium salts are widely used as arylating reagents for C–C and C–X bond formation. Meanwhile, synthetic applications of cyclic iodoniums are relatively rare although they offer the opportunity to set up reaction cascades. We demonstrate an atom and step economical three-component reaction involving cyclic diphenyleneiodoniums, alkynes, and boronic acids, resulting in the construction of methylidenefluorenes in a single operation. Our route enables facile access to both symmetrical and unsymmetrical methylidenefluorene derivatives, compounds that have attracted interest due to their optical properties.

Synthesis of highly substituted N-(furan-3-ylmethylene)benzenesulfonamides by a gold(I)-catalyzed oxidation/1,2-alkynyl migration/cyclization cascade.

A variety of N-(furan-3-ylmethylene)benzenesulfonamides were obtained by a gold(I)-catalyzed cascade reaction from easily accessible starting materials. The reaction pathway involves a rarely observed 1,2-alkynyl migration onto a gold carbenoid. This observation further enriches gold carbenoid chemistry with regard to group migration.

Autotandem catalysis: synthesis of pyrroles by gold-catalyzed cascade reaction.

A novel synthesis of substituted pyrroles by a gold(I)-catalyzed cascade reaction has been developed. The reaction proceeded with an autotandem catalysis consisting of an initial addition of gold-acetylide to an acetal moiety and was followed by gold-catalyzed 5-endo-dig cyclization and aromatization. Gold catalysts play a dual role in activating nucleophilicity or electrophilicity of terminal acetylenes by forming gold-acetylides or by π-coordination. The formal (3 + 2) annulation of two components provided a variety of substituted pyrroles in a modular fashion.

ChemInform Abstract: Synthesis of Highly Substituted 3‐Formylfurans by a Gold(I)‐Catalyzed Oxidation/1,2‐Alkynyl Migration/Cyclization Cascade.

3-Formylfuran derivatives are core structures of a variety of bioactive natural products. However, procedures for their preparation are still rare and generally inefficient in terms of atom economy: These methods require multiple steps or harsh reaction conditions and show selectivity problems. An efficient gold(I)-catalyzed cascade reaction that leads to 3-formylfurans from easily accessible starting materials is now described. A wide variety of 3-formylfurans were obtained from the corresponding symmetric and unsymmetric 1,4-diyn-3-ols in the presence of an N-oxide in good to excellent yields. Isotope-labeling experiments as well as DFT calculations support a mechanism in which, after an initial oxygen transfer, a 1,2-alkynyl migration is favored over a hydride shift; a cyclization ensues to afford the desired functionalized furan core.

ChemInform Abstract: Broensted Acid Catalyzed Cascade Reactions of 2‐[(2‐Aminophenyl)ethynyl]phenylamine Derivatives with Aldehydes: A New Approach to the Synthesis of 2,2′‐Disubstituted 1H,1′H‐3,3′‐Biindoles.

ChemInform Abstract: Broensted Acid Catalyzed Cascade Reactions of 2‐[(2‐Aminophenyl)ethynyl]phenylamine Derivatives with Aldehydes: A New Approach to the Synthesis of 2,2′‐Disubstituted 1H,1′H‐3,3′‐Biindoles.

Lewis acid catalyzed cascade reaction to carbazoles and naphthalenes via dehydrative [3 + 3]-annulation.

A novel Lewis acid catalyzed dehydrative [3 + 3]-annulation of readily available benzylic alcohols and propargylic alcohols was developed to give polysubstituted carbazoles and naphthalenes in moderate to good yields with water as the only byproduct. The reaction was presumed to proceed via a cascade process involving Friedel-Crafts-type allenylation, 1,5-hydride shift, 6π-eletrocyclization, and Wagner-Meerwein rearrangement.

Synthesis of Fully Substituted 3‐Formyl‐4‐iodofurans via a Gold(I)‐Catalyzed Oxidation/1,2‐Alkynyl Migration/Cyclization/Iodination Cascade

AbstractA highly efficient gold(I)‐catalyzed cascade reaction for the synthesis of fully substituted 3‐formyl‐4‐iodofurans has been developed. Mechanistic investigations indicate a reaction pathway that involves a direct iodination reaction of the organogold intermediate via functionalization of the AuC(sp2) bond, instead of a direct iodination of the 3‐formylfurans.magnified image

ChemInform Abstract: Benzofuran Derivatives from Alkynyl‐Substituted Benzynes and Aryl Halides.

A palladium(0)-catalyzed cascade reaction for the efficient synthesis of 2,3-disubstituted benzofuran derivatives 3 containing a 3-trisubstituted alkene functional group in moderate yields from alkynyl-substituted benzynes 1 and aryl halides 2 has been developed. This method provides an efficient and alternative approach to benzofurans which are very useful heterocyclic compounds with biological and pharmacological potentials. A plausible mechanism involving intramolecular ene reaction, intermolecular insertion, and β-H elimination is proposed.

ChemInform Abstract: Asymmetric Palladium(II)‐Catalyzed Cascade Reaction Giving Quaternary Amino Succinimides by 1,4‐Addition and a Nef‐Type Reaction.

AbstractAll products are isolated with <96% d.e..

FeCl3-Catalyzed Cascade Reaction: An Efficient Approach to Functionalized Coumarin Derivatives

An efficient and environmentally benign synthesis of 3-substituted or 3,4-disubstituted coumarins was accomplished via iron(III) chloride–catalyzed cascade reactions of salicylaldehydes and activated methylene compounds. The reaction preceded cleanly under mild reaction conditions to provide the desired coumarin derivatives in good to excellent yields.

Gold(I) as an Artificial Cyclase: Short Stereodivergent Syntheses of (−)‐Epiglobulol and (−)‐4β,7α‐ and (−)‐4α,7α‐Aromadendranediols

AbstractThree natural aromadendrane sesquiterpenes, (−)‐epiglobulol, (−)‐4β,7α‐aromadendranediol, and (−)‐4α,7α‐aromadendranediol, have been synthesized in only seven steps in 12, 15, and 17 % overall yields, respectively, from (E,E)‐farnesol by a stereodivergent gold(I)‐catalyzed cascade reaction which forms the tricyclic aromadendrane core in a single step. These are the shortest total syntheses of these natural compounds.

Gold(I) as an artificial cyclase: short stereodivergent syntheses of (-)-epiglobulol and (-)-4β,7α- and (-)-4α,7α-aromadendranediols.

Three natural aromadendrane sesquiterpenes, (−)-epiglobulol, (−)-4β,7α-aromadendranediol, and (−)-4α,7α-aromadendranediol, have been synthesized in only seven steps in 12, 15, and 17 % overall yields, respectively, from (E,E)-farnesol by a stereodivergent gold(I)-catalyzed cascade reaction which forms the tricyclic aromadendrane core in a single step. These are the shortest total syntheses of these natural compounds.

Brønsted Acid Catalyzed Cascade Reactions of 2-[(2-Aminophenyl)ethynyl]phenylamine Derivatives with Aldehydes: A New Approach to the Synthesis of 2,2′-Disubstituted 1H,1′H-3,3′-Biindoles

An unusual Brønsted acid catalyzed cascade reaction of 2-[(2-aminophenyl)ethynyl]phenylamine derivatives with aryl(heteroaryl)aldehydes to afford an efficient alternative entry into 2,2'-disubstituted-1H,1'H-3,3'-biindoles under metal-free conditions is reported.

Synthesis of Highly Substituted 3‐Formylfurans by a Gold(I)‐Catalyzed Oxidation/1,2‐Alkynyl Migration/Cyclization Cascade

3-Formylfuran derivatives are core structures of a variety of bioactive natural products. However, procedures for their preparation are still rare and generally inefficient in terms of atom economy: These methods require multiple steps or harsh reaction conditions and show selectivity problems. An efficient gold(I)-catalyzed cascade reaction that leads to 3-formylfurans from easily accessible starting materials is now described. A wide variety of 3-formylfurans were obtained from the corresponding symmetric and unsymmetric 1,4-diyn-3-ols in the presence of an N-oxide in good to excellent yields. Isotope-labeling experiments as well as DFT calculations support a mechanism in which, after an initial oxygen transfer, a 1,2-alkynyl migration is favored over a hydride shift; a cyclization ensues to afford the desired functionalized furan core.

ChemInform Abstract: Efficient One‐Pot Synthesis of Biologically Interesting Diverse Furo[2,3‐b]pyran‐6‐ones by Rhodium(II)‐Catalyzed Cascade Reactions of Diazo Compound with Ethynyl Compounds.

Rhodium(II)-catalyzed reactions of diazo compound and a variety of ethynyl compounds were carried out. These reactions provide a rapid route for preparing a variety of furo[2,3-b]pyran-6-one derivatives in one-pot via cascade reactions of metal carbenoid reaction/ketene formation/[2þ2]cycloaddition/ring expansion.