Br?nsted acid catalyzed addition of N^1-p-methyl toluenesulfonyl triazole to olefins for the preparation of N^2-alkyl 1,2,3-triazoles with high N^2-selectivity

An efficient new method has been developed to synthesize N2‐alkyl 1,2,3‐triazole products by tol‐uenesulfonic acid （TsOH） catalyzed addition of N1‐Ts substituted 1,2,3‐triazoles to olefins. The reac‐tions of monosubstituted and unsubstituted triazole substrates with various olefins, including vinyl esters, are explored.

Organic Brønsted Acid-Catalyzed Stereoselective Cationic RAFT Polymerization:The Effect of RAFT Agents

The tacticity of vinyl polymers is a key factor affecting the properties of materials.Recently,organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective cationic reversible addition-fragmentation chain transfer(RAFT)polymerizations of vinyl ethers,in which the use of RAFT agents could allow the control the molecular weight and tacticity of polymer products simultaneously.However,the effect of RAFT agents on the tacticity-regulation remains elusive and lacks of investigation.In this study,we synthesized four types of RAFT agents and evaluated their influence in the stereoselective cationic polymerization of isobutyl vinyl ether in the presence of PADI as a Brønsted acid catalyst,which unveils that the Z group of RAFT agents could not only affect the polydispersity of the products,but also exert a profound effect on the stereoselectivity.After extensive screening of the RAFT agents,high stereoregularity(isotacticity,90%m)was obtained when using dithiocarbonate ester-type RAFT agents with a benzyloxy Z group.

Oxidative cyclization of allyl compounds and isocyanide: A facile entry to polysubstituted 2-cyanopyrroles

A facile Tf OH-catalyzed oxidative cyclization of allyl compounds and isocyanide has been developed with the assistance of DDQ, where isocyanide is used as the crucial "N" and "CN" sources. Highly functionalized 2-cyanopyrroles are constructed efficiently through a new formal [3 + 2] mode, demonstrating diverse reactivity and synthetic utility in organic chemistry. 2-Cyanopyrrole is converted into a nucleobase analogue of Remdesivir and 5H-pyrrolo[2,1-a]isoindole through a three-step or a two-step sequence, respectively. This protocol features broad substrate scope, operational simplicity and good functional group tolerance.

Highly Stereoselective Positional Isomerization of Styrenes via Acid-Catalyzed Carbocation Mechanism

The first transition metal-free highly stereoselective positional isomerization of various α-alkyl styrenes through a carbocation mech-anism triggered strategy is developed by using AI(OTf)_(3) as a hidden Br0nsted acid catalyst,which provides facile access to value-added acyclic tri-and tetra-substituted alkenes in good yields with high stereoselectivity under mild conditions.

One-pot remote desymmetrization/Peterson-olefination for the construction of silicon-stereogenic silyl ethers

Chiral silyl ethers and silanols are important synthetic intermediates and bioactive compounds.In this work,we developed a onepot remote desymmetrization/Peterson-olefination of silacyclopentene oxides with benzoic acids in the presence of Martin’s sulfurane.This new methodology not only realizes the atom-economy of Peterson olefination,but also represents a catalytic method for synthesis of silicon-stereogenic silyl ethers.Using a bulky chiral phosphoric acid 4i as organocatalyst,the reactions proceeded efficiently to afford various olefin-functionalized organosilyl ethers in excellent diastereoelectivities(up to 25/1 d.r.)and high enantioselectivities(up to 94%ee).