Structural and Catalytic Insight into the Unique Pentacyclic Triterpene Synthase TwOSC.

The oxidosqualene cyclase (OSC) catalyzed cyclization of the linear substrate (3S)-2,3-oxidosqualene to form diverse pentacyclic triterpenoid (PT) skeletons is one of the most complex reactions in nature. Friedelin has a unique PT skeleton involving a fascinating nine-step cation shuttle run (CSR) cascade rearrangement reaction, in which the carbocation formed at C2 moves to the other side of the skeleton, runs back to C3 to yield a friedelin cation, which is finally deprotonated. However, as crystal structure data of plant OSCs are lacking, it remains unknown why the CSR cascade reactions occur in friedelin biosynthesis, as does the exact catalytic mechanism of the CSR. In this study, we determined the first cryogenic electron microscopy structure of a plant OSC, friedelin synthase, from Tripterygium wilfordii Hook. f (TwOSC). We also performed quantum mechanics/molecular mechanics simulations to reveal the energy profile for the CSR cascade reaction and identify key residues crucial for PT skeleton formation. Furthermore, we semirationally designed two TwOSC mutants, which significantly improved the yields of friedelin and ß-amyrin, respectively.

Direct Fluoroacylation of Indole with Perfluoroalkyl Iodides.

Functionalization of perfluoroalkyl compounds has shown huge potential in synthetic chemistry and drug development. Herein, we report a one-pot tandem perfluoroalkylation-defluorination reaction of indole, perfluoroalkyl iodide, and water in the presence of Na2S2O4. A wide array of indole derivatives were efficiently accessed with good yields under mild reaction conditions. The reaction is believed to undergo perfluoroalkylation and follow the defluorination hydrolysis pathway. This study represents an alternative approach for defluorination functionalization.

Direct fluoroalkylthiolation of indoles with iodofluoroethane enabled by Na2S2O4.

In this paper, we report an efficient approach for the direct fluoroalkylthiolation of indoles with iodofluoroethane in the presence of Na2S2O4. In this work, we employed readily available iodofluoroethane and Na2S2O4 as fluoroalkylthiolation reagents, featuring mild conditions and a wide range of indole substrates. In addition, fluoroalkylthiolated 2,3'-biindole derivatives can also be prepared by this method.

Hexakis [60]Fullerene Adduct-Mediated Covalent Assembly of Ruthenium Nanoparticles and Their Catalytic Properties.

The C66 (COOH)12 hexa-adduct has been successfully used as a building block to construct carboxylate bridged 3D networks with very homogeneous sub-1.8 nm ruthenium nanoparticles. The obtained nanostructures are active in nitrobenzene selective hydrogenation.

Facile synthesis of trifluoroethyl compounds by the Suzuki cross-coupling reactions of CF3CH2OTs with arylboronic acids.

This research provides a novel approach for introducing a CF3CH2 group onto aromatic rings using Pd(OAc)2/palladacycle as a catalyst for the Suzuki cross-coupling reaction of CF3CH2OTs (OTs = 4-methylbenzene sulfonate) with arylboronic acids.

Arylation of 2-substituted pyridines via Pd-catalyzed decarboxylative cross-coupling reactions of 2-picolinic acid.

The novel palladium-catalyzed decarboxylative cross-coupling reactions of 2-picolinic acid with aryl and heteroaryl bromides including benzenes, naphthalenes, pyridines and quinolines for C-C bond formation have been successfully achieved.