Straightforward Synthesis of Bis[(trifluoromethyl)sulfonyl]ethylated Isocoumarins from 2-Ethynylbenzoates.

Herein, we report a facile isocoumarin and isoquinolone preparation by taking advantage of an initial bis(triflyl)ethylation [triflyl = (trifluoromethyl)sulfonyl] reaction, followed by heterocyclization, which contrasts with our previous results on cyclobutene formation. The efficiency of the catalyst- and irradiation-free heterocyclization/bis(triflyl)ethylation sequence showed exquisite dependence on the electronic nature of the substituents at the 2-ethynylbenzoate(benzamide) precursors. Molecular docking of model bis(triflyl)ethylated isocoumarins on human acetylcholinesterase (hAChE) revealed promising biological activities through selective coordination on both the catalytic active site and peripheral active site.

Synthesis of Polycyclic Aromatic Hydrocarbons Decorated by Fluorinated Carbon Acids/Carbanions.

The carboarylation reaction of biphenyl-alkynes was successfully triggered by electrophilic attack of 1,1-bis(triflyl)ethylene on the alkyne moiety to give polycyclic aromatic hydrocarbons (PAHs) decorated by superacidic carbon acid functionality. Neutralisation of thus obtained acids with NaHCO yielded the corresponding sodium salts, which showed improved solubility in both aqueous and organic solvents.

A catalyst-free bis(triflyl)ethylation/benzannulation reaction: rapid access to carbazole-based superacidic carbon acids from alkynols.

Carbazoles possessing TfCHCH groups were obtained by the reaction of 1-(indol-2-yl)but-3-yn-1-ols with in situ-generated TfC[double bond, length as m-dash]CH through vicinal difunctionalisation of the alkyne moiety, where the vinyl-type carbocation intermediate was selectively attacked by the indole moiety and not by the carbanion moiety.

A Facile Synthesis of Blue Luminescent [7]Helicenocarbazoles Based on Gold-Catalyzed Rearrangement-Iodonium Migration and Suzuki-Miyaura Benzannulation Reactions.

New azahelicenes having interesting photophysical properties have been prepared in a four-step sequence. These [7]helicenocarbazoles are efficient blue luminophores, demonstrating the utility of gold catalysis in the preparation of advanced materials.

Investigation of the Passerini and Ugi reactions in β-lactam aldehydes. Synthetic applications.

Passerini (P-3CR) and Ugi (U-4CR) reactions were investigated in 4-oxoazetidine-2-carboxaldehydes, affording the corresponding Passerini and Ugi adducts with moderate diastereoselectivity in high yields. Fortunately, the obtained mixtures of isomers syn/anti were separated in most cases. The scope of both IMCRs has been studied using a variety of isocyanides, carboxylic acids and amines.

Cyclization reactions of bis(allenes) for the synthesis of polycarbo(hetero)cycles.

The chemistry of allenes is an appealing topic which fascinates chemists nowadays. Their reactivity and versatility makes this skeleton a useful moiety to create a great variety of structures depending on the functional groups attached and the reaction conditions used. Recently, there is a growing interest in the study of the reactivity of bis(allenes) inspired in the chemistry developed in simple allenes.

Organocatalyzed three-component Ugi and Passerini reactions of 4-oxoazetidine-2-carbaldehydes and azetidine-2,3-diones. Application to the synthesis of γ-lactams and γ-lactones.

The organocatalyzed U-3CR of 4-oxoazetidine-2-carbaldehydes has been studied. In addition, the organocatalyzed P-3CR of 4-oxoazetidine-2-carbaldehydes and azetidine-2,3-diones has been described for the first time. U-3CR and P-3CR adducts have been obtained in good yields and reasonable diastereoselectivities.

Regio- and diastereoselective synthesis of β-lactam-triazole hybrids via Passerini/CuAAC sequence.

Passerini (P-3CR) and Passerini-Smiles reactions were investigated in azetidine-2,3-diones, affording the corresponding 3,3-disubstituted-β-lactams with complete diastereoselectivity in high yields. The study has been carried out using different isocyanides, carboxylic acids, and phenols showing the scope of both reactions. In addition, the regioselective synthesis of highly functionalized β-lactam-triazole hybrids has been developed via a Passerini/CuAAC sequence.

Highly reactive 4-membered ring nitrogen-containing heterocycles: Synthesis and properties.

4-Membered nitrogen-containing heterocycles, such as β-lactams (ie, 2-azetidinones) and azetidines, are useful substrates in organic chemistry for the design and preparation of biologically active compounds by functionalization of the different positions of the ring. In addition, these compounds are versatile building blocks for the synthesis of other types of nitrogen-containing compounds with potential biological properties. This review summarizes recent data regarding the preparation and properties of 4-membered nitrogen-containing heterocyclic rings, as well as their biological activities.

Exploiting [2+2] cycloaddition chemistry: achievements with allenes.

The allene moiety represents an excellent partner for the [2+2] cycloaddition with alkenes and alkynes, affording the cyclobutane and cyclobutene skeletons in a single step. This strategy has been widely studied under thermal, photochemical and microwave induced conditions. More recently, the use of transition metal catalysis has been introduced as an alternative relying on the activation of the allenic component.

Rhodium-catalyzed synthesis of 3-hydroxy-beta-lactams via oxonium ylide generation: three-component reaction between azetidine-2,3-diones, ethyl diazoacetate, and alcohols.

3-Substituted-3-hydroxy-beta-lactams, with two new adjacent stereogenic centers, have been prepared in a single step by a rhodium-catalyzed, three-component reaction between azetidine-2,3-diones, ethyl diazoacetate, and alcohols. Good to moderate stereoselectivity was obtained depending on the alcohol used. The stereochemistry of the new centers has been undoubtedly assigned by single crystal X-ray diffraction.

Carbonyl allenylation/free radical cyclization sequence as a new regio- and stereocontrolled access to bi- and tricyclic beta-lactams.

A novel approach to racemic and enantiopure nonconventional fused bi- and tricyclic beta-lactams has been developed by using regio- and stereocontrolled intramolecular free radical reactions in monocyclic 2-azetidinone-tethered allenynes and haloallenes. The access to allene cyclization precursors was achieved by metal-mediated carbonyl allenylation of appropriately substituted 4-oxoazetidine-2-carbaldehydes in an aqueous environment. The tin-promoted radical cyclizations of allene-beta-lactams are totally regioselective for the central allenic carbon, providing bi- and tricyclic beta-lactams containing a seven-membered ring.

Synthesis of strained tricyclic beta-lactams by intramolecular [2+2] cycloaddition reactions of 2-azetidinone-tethered enallenols: control of regioselectivity by selective alkene substitution.

A convenient metal-free methodology for the preparation of structurally novel, strained tricyclic beta-lactams containing a cyclobutane ring has been developed. The first examples accounting for the intramolecular [2+2] cycloaddition reactions in beta-lactams have been achieved by the thermolysis of 2-azetidinone-tethered enallenols, which have been prepared in aqueous media by regio- and diastereoselective indium-mediated carbonyl allenylation of 4-oxoazetidine-2-carbaldehydes. Notably, the regioselectivity of the cycloaddition can be tuned in the allene component just by a subtle variation in the substitution pattern of the alkene component.

Straightforward asymmetric entry to highly functionalized 3-substituted 3-hydroxy-beta-lactams via Baylis-Hillman or bromoallylation reactions.

The reaction of various activated vinyl systems, including 2-cyclopenten-1-one, with enantiopure azetidine-2,3-diones 1 was promoted by DABCO to afford the corresponding optically pure Baylis-Hillman adducts 2 without detectable epimerization. However, the reaction of alpha-keto lactams 1 with but-3-yn-2-one was not as successful, giving the corresponding beta-halo Baylis-Hillman adduct in low yield. Metal-mediated bromoallylation reaction between 2,3-dibromopropene and azetidine-2,3-diones 1 was investigated in aqueous media.

Structurally novel Bi- and tricyclic beta-lactams via [2 + 2] cycloaddition or radical reactions in 2-azetidinone-tethered enallenes and allenynes.

[reaction: see text] Thermolysis of beta-lactam-tethered enallenyl alcohols gave tricyclic ring structures via a formal [2 + 2] cycloaddition of the alkene with the distal bond of the allene, while the tin-promoted radical cyclization in 2-azetidinone-tethered allenynes proceeded to provide bicyclic beta-lactams containing a medium-sized ring. The access to cyclization precursors was achieved by regio- and stereoselective metal-mediated carbonyl allenylation of 4-oxoazetidine-2-carbaldehydes in an aqueous environment.

A novel one-step approach for the preparation of alpha-amino acids, alpha-amino amides, and dipeptides from azetidine-2,3-diones.

A remarkable reaction of azetidine-2,3-diones with primary as well as secondary amines, and water is presented. Simply by varying the nucleophile, an unprecedented one-step synthesis of alpha-amino acids, alpha-amino amides, and dipeptides, was developed in both the racemic and optically pure forms. The current mechanistic hypothesis invokes a concerted process involving CO extrusion.

New domino transposition/intramolecular Diels-Alder reaction in monocyclic allenols: a general strategy for tricyclic compounds.

A novel and direct synthetic strategy to prepare fused tricycles has been developed from monocyclic allenols, masked functionalized dienes, which underwent a domino allenol transposition/intramolecular Diels-Alder reaction.

Additions of allenyl/propargyl organometallic reagents to 4-oxoazetidine-2-carbaldehydes: novel palladium-catalyzed domino reactions in allenynes.

Metal-mediated carbonyl allenylation and propargylation of 4-oxoazetidine-2-carbaldehydes were investigated in aqueous environment. Different propargyl bromide and metal promoters showed varied regio- and stereoselectivities on product formation. In addition, an unprecedented one-pot stereoselective synthesis of beta-chlorinated allylic alcohols, which can also be considered as functionalized allylsilanes, has been developed, which involves tin(IV) chloride-mediated reaction of propargyltrimethylsilane and 4-oxoazetidine-2-carbaldehydes.