Enantioselective Reductive N-Cyclization-Alkylation Reaction of Alkene-Tethered Oxime Esters and Alkyl Iodides by Nickel Catalysis.

Asymmetric cross-electrophile difunctionalization of tethered alkenes has become a powerful tool for the production of chiral cyclic scaffolds; however, the current studies all focus on carbocyclization reactions. Herein, we report an N-cyclization-alkylation reaction and thus showcase the potential of heterocyclization for accessing new enantioenriched cyclic architectures. This work establishes a new approach for enantioselective aza-Heck cyclization/cross-coupling sequence, which remains a long-standing unsolved challenge for the synthetic community. The reaction proceeds with primary, secondary, and a few tertiary alkyl iodides, and the use of newly defined ligands gave highly enantioenriched pyrrolines with improved molecular diversity under mild conditions. The presence of imine functionality allows for further structural variations.

A Review on Phytochemicals of the Genus Maytenus and Their Bioactive Studies.

The genus Maytenus is a member of the Celastraceae family, of which several species have long been used in traditional medicine. Between 1976 and 2021, nearly 270 new compounds have been isolated and elucidated from the genus Maytenus. Among these, maytansine and its homologues are extremely rare in nature. Owing to its unique skeleton and remarkable bioactivities, maytansine has attracted many synthetic endeavors in order to construct its core structure. In this paper, the current status of the past 45 years of research on Maytenus, with respect to its chemical and biological activities are discussed. The chemical research includes its structural classification into triterpenoids, sesquiterpenes and alkaloids, along with several chemical synthesis methods of maytansine or maytansine fragments. The biological activity research includes activities, such as anti-tumor, anti-bacterial and anti-inflammatory activities, as well as HIV inhibition, which can provide a theoretical basis for the better development and utilization of the Maytenus.

Platinum-catalyzed tandem cycloisomerization reaction of benzoendiynyl esters: regioselective long-range 1,5-acyl migration.

A Pt(II)-catalyzed intramolecular chemo- and regioselective pentannulation/long-range 1,5-acyl migration reaction is described. This cascade cycloisomerization protocol produces a wide variety of benzofulvene diketones in good to excellent yields with exclusively the Z configuration of the exocyclic double bond of the final product. The (18)O isotope experiment together with (13)C NMR, HRMS, and HMBC analyses confirmed an interesting long-range acyl rearrangement process in this transformation.

4D-QSAR and MIA-QSAR Studies of Aminobenzimidazole Derivatives as Fourth-generation EGFR Inhibitors.

BACKGROUND: The epidermal growth factor receptor (EGFR) protein has been intensively studied as a therapeutic target for non-small cell lung cancer (NSCLC). The aminobenzimidazole derivatives as the fourth-generation EGFR inhibitors have achieved promising results and overcame EGFR mutations at C797S, del19 and T790M in NSCLC. OBJECTIVE: In order to understand the quantitative structure-activity relationship (QSAR) of aminobenzimidazole derivatives as EGFRdel19 T790M C797S inhibitors, the four-dimensional QSAR (4D-QSAR) and multivariate image analysis (MIA-QSAR) have been performed on the data of 45 known aminobenzimidazole derivatives. METHODS: The 4D-QSAR descriptors were acquired by calculating the association energies between probes and aligned conformational ensemble profiles (CEP), and the regression models were established by partial least squares (PLS). In order to further understand and verify the 4D-QSAR model, MIA-QSAR was constructed by using chemical structure pictures to generate descriptors and PLS regression. Furthermore, the molecular docking and averaged noncovalent interactions (aNCI) analysis were also performed to further understand the interactions between ligands and the EGFR targets, which was in good agreement with the 4D-QSAR model. RESULTS: The established 4D-QSAR and MIA-QSAR models have strong stability and good external prediction ability. CONCLUSION: These results will provide theoretical guidance for the research and development of aminobenzimidazole derivatives as new EGFRdel19 T790M C797S inhibitors.

Two new triterpenes isolated from Maytenus guangxiensis C. Y. Cheng et W. L. Sha and their antiproliferative activities.

Two new triterpenes, 3ß, 7ß-dihydroxyolean-12-en-11-one (1) and 3ß-O-acetyl-7ß-hydroxyolean-12-en-11-one (2), along with four known triterpenes 3ß-hydroxyolean-12-en-11-one (3), ß-amyrin (4), lup-20(29)-ene-1ß, 3ß-diol (5) and 1ß, 3ß-dihydroxy-urs-9(11)-12-diene (6), were isolated from the stems and leaves of Maytenus guangxiensis C. Y. Cheng et W. L. Sha. Their structures were elucidated using 1D and 2D NMR spectroscopy as well as MS and IR experiments. Compounds (3-6) were isolated from M. guangxiensis for the first time. Compounds 1-6 were evaluated for their antiproliferative activities against Eca-109, PANC-1, EJ and HeLa cell lines. The results showed that compounds 1-6 displayed a certain degree of inhibitory effects against the proliferation of various human cancer cell lines.

Dual nickel and Lewis acid catalysis for cross-electrophile coupling: the allylation of aryl halides with allylic alcohols.

Controlling the selectivity in cross-electrophile coupling reactions is a significant challenge, particularly when one electrophile is much more reactive. We report a general and practical strategy to address this problem in the reaction between reactive and unreactive electrophiles by a combination of nickel and Lewis acid catalysis. This strategy is used for the coupling of aryl halides with allylic alcohols to form linear allylarenes selectively. The reaction tolerates a wide range of functional groups (e.g. silanes, boronates, anilines, esters, alcohols, and various heterocycles) and works with various allylic alcohols. Complementary to most current routes for the C3 allylation of an unprotected indole, this method provides access to C2 and C4-C7 allylated indoles. Preliminary mechanistic experiments reveal that the reaction might start with an aryl nickel intermediate, which then reacts with Lewis acid activated allylic alcohols in the presence of Mn.

AgOTf-catalyzed electrophilic cyclization of triynols with NXS: rapid synthesis of densely trisubstituted naphthalenes and quinolines.

A silver triflate-catalyzed electrophilic cyclization reaction of acyclic triynols with NXS (X=I, Br) under mild conditions is reported. Three reactive functional groups, such as a carbonyl group, an alkyne group, and a halogen, could be selectively installed at the C1, C2, and C3 positions to obtain the naphthalene and quinoline products, respectively. The obtained densely trisubstituted products could be further transformed into more complex aromatic products by manipulating the alkynyl moiety and the other two functional groups as synthons.