A concise total synthesis of (+)-propindilactone G, a nortriterpenoid isolated from the stems Schisandra propinqua var. propinqua, has been achieved for first time. The key steps include an asymmetric Diels-Alder reaction, Pauson-Khand Pd-catalyzed reductive hydrogenolysis and oxidative heterocoupling reaction. These reactions enabled G in only 20 steps. As consequence our synthetic studies, structure revised.

A low-voltage ride-through (LVRT) strategy for a doubly fed induction generator (DFIG) with switch-type fault current limiter (STFCL) is presented in this paper. The STFCL composed of fault-current-limiting inductors, isolation transformers, diode bridge, semiconductor switch, snubber capacitor, and energy absorption bypass. can insert inductors series the stator branches on occurrence grid fault, which limit rotor overcurrent weaken back electromagnetic force voltage simultaneously. safety...

The asymmetric total synthesis of janthinoid A has been accomplished for the first time in 14 steps without using a protecting group. trans-decalin subunit and rigid oxabicyclo[3.2.1]octane motif were constructed via an epoxide-initiated cationic π-cyclization reaction Fe(ClO4)3-mediated oxidative cascade cyclization reaction, respectively.

The enantioselective synthesis of (−)-pavidolide B (1) was achieved in a linear sequence 10 steps. key steps are (a) an organocatalytic cyclopropanation; (b) radical-based cascade annulation for the regio- and diastereo-selective highly functionalized lactone 3 bearing characteristic tricyclic core seven contiguous stereocenters; (c) sequential ring-closing metathesis reaction RhCl3-catalyzed double bond isomerization to form seven-membered D ring B.

Asymmetric total synthesis of structurally intriguing and highly oxygenated lancifodilactone G acetate (7) has been achieved for the first time in 28 steps from a cheap commodity chemical, 2-(triisopropylsiloxy)-1,3-butadiene.

The collective synthesis of skeletally diverse Stemona alkaloids featuring tailored dyotropic rearrangements β-lactones as key elements is described. Specifically, three typical 5/7/5 tricyclic skeletons associated with stemoamide, tuberostemospiroline and parvistemonine were first accessed through chemoselective involving alkyl, hydrogen, aryl migration, respectively. By the rational manipulation substrate structures reaction conditions, these proceeded excellent efficiency, good...

Palladium-catalyzed denitrogenative Suzuki and carbonylative reactions of benzotriazoles with boronic acids have been achieved through the<italic>in situ</italic>generation of<italic>ortho</italic>-amino-arenediazonium species.

Abstract The Diels–Alder reaction stands as one of the most pivotal transformations in organic chemistry. Its efficiency, marked by formation two carbon‐carbon bonds and up to four new stereocenters a single step, underscores its versatility indispensability synthesizing natural products pharmaceuticals. significant stereoselectivity feature is “endo rule”. While this rule underpins predictability stereochemical outcomes, it also challenges achieving opposite diastereoselectivity, making exo...

Performance of three kinds bridge-type fault current limiters (BTFCLs) for enhancing low-voltage-ride-through (LVRT) capability DFIG is evaluated in this paper. The common BTFCL can effectively enhance the LVRT DFIG. However, fault-current-limiting inductor (FCLI) periodically inserted into stator circuit under normal operation compensating power losses FCLI. insertion FCLI induces voltage spikes, which causes significant flux and electromagnetic torque oscillations. One feasible way to...

Abstract The first total syntheses of asperchalasines A–E, a collection unprecedented merocytochalasans, are reported. Aspochalasin B, key tricyclic cytochalasan monomer, was synthesized through unified approach that hinges on Diels–Alder reaction and ring‐closing metathesis reaction. bioinspired reactions aspochalasin B with different epicoccine precursors were then explored, which enabled the divergent access heterodimers B–E as well related congeners. Furthermore, heterotrimer...

Abstract A novel method for the concise synthesis of cyclohepta[b]indoles in high yields was developed. The involves a visible‐light‐induced, photocatalyzed [2+2]‐cycloaddition/ retro‐Mannich‐type reaction enaminones. Experimental and computational studies suggested that is photoredox process initiated by single‐electron oxidation an enaminone moiety, which undergoes subsequent cyclobutane formation rapidly fragmentation radical‐cation state to form cyclohepta[b]indoles.

Abstract An enantioselective synthesis of (+)‐8‐ epi ‐xanthatin hinging on a chiral phosphoric acid catalyzed tandem allylboration/lactonization reaction is reported. With as the precursor, collective series synthetically challenging xanthanolides was also accomplished. Among them, xanthipungolide, one most complex xanthanolide monomers, accessed through bioinspired double‐bond isomerization/6π electronic cyclization/intramolecular Diels–Alder reaction, and pungiolides A, B, D, E, L–N, group...

Pd-Catalyzed denitrogenative functionalizations of benzotriazoles with alkenes and 1,3-dienes have been developed, which enable the rapid access diverse<italic>ortho</italic>-amino styrenes 2-vinylindolines, respectively.

Abstract An unprecedented strain‐driven dyotropic rearrangement of α‐methylene‐β‐lactones has been realized, which enables the efficient access a wide range α‐methylene‐γ‐butyrolactones displaying remarkable structural diversity. Several appealing features reaction, including excellent efficiency, high stereospecificity, predictable chemoselectivity and broad substrate scope, render it powerful tool for synthesis MBL‐containing molecules either natural or synthetic origin. Both experimental...

Arsenic (As) biomethylation is an important component of the As biogeochemical cycle, which produces methylarsenite [MAs(III)] as intermediate product. Its high toxicity used by some microbes antibiotic to kill off other and gain a competitive advantage. Some aerobic have evolved detoxification mechanism demethylate MAs(III) via dioxygenase C–As lyase ArsI. How demethylated under anoxic conditions unclear. We found that nitrate addition flooded paddy soil enhanced demethylation. A...

An unprecedented [2 + 3] annulation of N-sulfonyl-1,2,3-triazoles with enaminones is reported for the access polysubstituted furans. The key to success transformations lies in use Rh(II)-Brønsted acid as cooperative catalysts. Unlike conventional annulations N-sulfony-l-1,2,3-triazoles, Rh(II)-azavinyl carbenes species play dual functions this work, enabled by cleavage C(sp2)-N bond. mechanism studies suggested that an intermolecular rearrangement TsNH- group crucial process.

In bacterial pathogenesis, virulence gene regulation is controlled by two-component regulatory systems. <i>Escherichia coli</i>, the EnvZ/OmpR system best understood as regulating expression of outer membrane proteins, but in <i>Salmonella enterica</i>, OmpR activates transcription SsrA/B located on <i>Salmonella</i> pathogenicity island 2 (SPI-2). The response regulator SsrB controls a type III secretory which effectors modify vacuolar and prevent its degradation via endocytic pathway....

The first total syntheses of rubialatins A and B, two newly discovered naphthohydroquinone dimers, were achieved with high efficiency elegancy through rationally designed biomimetic approaches. tandem ring contraction/Michael addition/aldol reaction followed by oxidation enabled the rapid access prerubialatin from readily available precursors, which then diverted into B via epoxidation photoinduced skeletal rearrangement, respectively. Moreover, several new rubialatin congeners also obtained...

Photoredox-catalyzed isomerization of γ-carbonyl-substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C-H bond activation. This catalytic redox-neutral process resulted in synthesis 1,4-dicarbonyl compounds. Notably, bearing tetrasubstituted olefins can also be transformed into Density functional theory calculations show that group at γ-position are beneficial formation alcohol radicals with high vertical electron affinity, which...

The synthesis of strained polycyclic systems from readily available precursors with a minimum number steps and regio- stereochemical control constitutes an important synthetic challenge. Herein, we report tandem reaction comprising Co-TMTU (tetramethyl thiourea)-catalyzed Pauson-Khand (PK) 6π-electrocyclization reactions for the formation highly core presilphiperfolanols. developed chemistry has been applied to total syntheses 4-epi-presilphiperfolan-8-ol 7-epi-presilphiperfolan-1-ol.

A cascade benzenethiol-mediated intramolecular [3 + 2] cycloaddition reaction between an allene and α,β-unsaturated aldehyde or ester is developed for the diastereoselective synthesis of [3.3.0] bicyclic system bearing two quaternary atoms at their bridgehead positions. Notably, these structurally complex systems can be found in a wide range natural products.