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Cytochrome P450 enzymes are known to catalyse bimodal oxidation of aliphatic acids via radical intermediates, which partition between pathways of hydroxylation and desaturation1,2. Developing analogous catalytic systems for remote C–H functionalization remains a significant challenge3–5. Here, we report the development of Cu(I)-catalysed bimodal dehydrogenation/lactonization reactions of synthetically common N-methoxyamides through radical abstractions of the γ-aliphatic C–H bonds. The feasibility of switching from dehydrogenation to lactonization is also demonstrated by altering reaction conditions. The use of a readily available amide as both radical precursor and internal oxidant allows for the development of redox-neutral C–H functionalization reactions with methanol as the sole side product. These C–H functionalization reactions using a Cu(I) catalyst with loading as low as 0.5 mol.% is applied to the diversification of a wide range of aliphatic acids including drug molecules and natural products. The exceptional compatibility of this catalytic system with a wide range of oxidatively sensitive functionality demonstrates the unique advantage of using a simple amide substrate as a mild internal oxidant.Use of N-methoxyamides as oxidants enables controllable, redox-neutral, green catalysis of bimodal dehydrogenation/lactonization reactions with methanol as the only by-product. [ABSTRACT FROM AUTHOR]

This study aimed to explore the impact of three corrosive ions—SO42−, Cl−, and Mg2+—on the hydration property of calcium sulphoaluminate (CSA) cement. Cement paste was prepared using three types of sea salt ion solutions with varying concentrations as mixing water. The experimental program encompassed assessments of porosity, compressive/flexural strength, heat of hydration, pH of pore solution, XRD, and SEM analysis. To modulate the hydration environment, Ordinary Portland cement (10%) was incorporated to elevate the pH and enhance the stability of ettringite, thereby facilitating the formation of additional C-S-H gel for the observation of M-S-H and other compounds. Findings revealed that the Cl− accelerated the hydration of CSA, resulting in heightened heat release. However, it also decreased the length-to-diameter ratio of ettringite, leading to cracking in CSA test blocks. The addition of SO42− resulted in elevated internal alkalinity, prompting alterations in hydration product types and subsequent reduction in CSA strength. Conversely, Mg2+ was observed to ameliorate the microstructure of CSA test blocks, diminishing porosity and augmenting strength. [ABSTRACT FROM AUTHOR]

We constructed a small library of indole terpenoid mimics using a hybridizing strategy to link various indole and α,β-unsaturated enone building blocks together. Prepared compounds were evaluated for the cytotoxicity against a panel of cancer cell lines. An indolyl ketone called JP18 was identified as a cell cycle regulator, and the underlying mechanism was investigated. [ABSTRACT FROM AUTHOR]

The first total synthesis of mycoleptodiscin A, a structurally unusual indolosesquiterpenoid possessing an ortho-benzoquinone motif, has been accomplished. A sulfone alkylation coupled two readily available fragments to give an aryl triene intermediate. The tetracyclic core of the molecule was assembled through a highly enantioselective iridium-catalyzed polyene cyclization. The benzylic homologation was achieved by a cationic cyanation. The indole motif was constructed via a copper-mediated intramolecular CN bond formation at a late stage. [ABSTRACT FROM AUTHOR]

The chemical synthesis of indole terpenoids of structural and biological interests has attracted remarkable attention. Here we report an Eu(fod)3-catalyzed indole conjugate addition reaction, which tolerates various acid-sensitive functional groups. A collection of indole terpenoid mimics have been prepared from natural product-derived α,β-unsaturated enones on the basis of this reaction. The further conversion of the indole adducts into more complex natural product-like molecules has also been demonstrated. [ABSTRACT FROM AUTHOR]

We have developed an intermolecular conjugate addition of 3a-pyrroloindoline/furoindoline radicals to α,β-unsaturated enones, through visible-light photoredox catalysis. Ir(ppy)2(dtbbpy) PF6 was found to be an effective promoter to initiate this reaction from readily available 3a-bromopyrroloindolines/furoindolines. This method was exploited to prepare a series of indole terpenoid-like compounds of potential biological interest. [ABSTRACT FROM AUTHOR]

The first total synthesis of the indolosesquiterpenoid mycoleptodiscin A is described. [ABSTRACT FROM AUTHOR]

The first total syntheses of taiwaniadducts B, C, and D have been accomplished. Two diterpenoid segments were prepared with high enantiopurity, both through Ir-catalyzed asymmetric polyene cyclization. A sterically demanding intermolecular Diels-Alder reaction promoted by Er(fod)3 assembled the scaffold of taiwaniadducts B and C. A carbonyl-ene cyclization forged the cage motif of taiwaniadduct D at a late stage, providing over 200 mg of this compound.

A divergent approach was developed toward the total synthesis of taiwaniaquinoids. An advanced intermediate 5a with trans A/B ring junction was concisely assembled by employing a Bi(OTf)3-catalyzed cationic cyclization and a Wolff-type ring contraction as key steps. This common intermediate was readily converted to racemic taiwaniaquinones A and F and taiwaniaquinols B and D, respectively.