Amino Turbo Chirality and Its Asymmetric Control.

A series of new targets containing 3 chiral elements of central, orientational, and turbo chirality have been designed and synthesized asymmetrically. The absolute configurations and conformations of these types of chirality were concurrently controlled by using chiral sulfonimine auxiliary and unambiguously determined by x-ray diffraction analysis. These targets include alpha unnatural amino acid derivatives, which may play an important role for drug design, discovery, and development.

C(sp)-C(sp) Lever-Based Targets of Orientational Chirality: Design and Asymmetric Synthesis.

In this study, the design and asymmetric synthesis of a series of chiral targets of orientational chirality were conducted by taking advantage of -sulfinylimine-assisted nucleophilic addition and modified Sonogashira catalytic coupling systems. Orientational isomers were controlled completely using alkynyl/alkynyl levers [C(sp)-C(sp) axis] with absolute configuration assignment determined by X-ray structural analysis. The key structural element of the resulting orientational chirality is uniquely characterized by remote through-space blocking.

Design and Asymmetric Control of Orientational Chirality by Using the Combination of C(sp)-C(sp) Levers and Achiral N-Protecting Group.

New chiral targets of orientational chirality have been designed and asymmetrically synthesized by taking advantage of N-sulfinyl imine-directed nucleophilic addition/oxidation, Suzuki-Miyaura, and Sonogashira cross-coupling reactions. Orientation of single isomers has been selectively controlled by using aryl/alkynyl levers [C(sp)-C(sp) axis] and tBuSO- protecting group on nitrogen as proven by X-ray diffraction analysis. The key structural characteristic of resulting orientational products is shown by remote through-space blocking manner.

Study on the Mechanism of Ru-Catalyzed Cyclization of Aromatic Amides with Allylphosphine Oxides.

The mechanism of Ru-catalyzed cyclization of aromatic amides with allylphosphine oxides is studied by density functional theory calculation (DFT). The results show that, first, a 5-membered Ru ring intermediate is formed by N-H and C-H diprotons via the concerted metalation-deprotonation mechanism (CMD) and then the allylphosphine oxide is inserted through the ring-extending reaction to form a 7-membered ring intermediate. Next, reduction elimination is followed via intramolecular hydrogen transfer isomerization.

Switchable synthesis of natural-product-like lawsones and indenopyrazoles through regioselective ring-expansion of indantrione.

Lawsones and indenopyrazoles are the prevalent structural motifs and building blocks in pharmaceuticals and bioactive molecules, but their synthesis has always remained challenging as no comprehensive protocol has been outlined to date. Herein, a metal-free, ring-expansion reaction of indantrione with diazomethanes, generated in situ from the N-tosylhydrazones, has been developed for the synthesis of lawsone and indenopyrazole derivatives in acetonitrile and alcohol solvents, respectively. It provides these valuable lawsone and pyrazole skeletons in good yields and high levels of diastereoselectivity from simple and readily available starting materials.

Can a Wanzlick-like equilibrium exist between dicoordinate borylenes and diborenes?

Boron chemistry has experienced tremendous progress in the last few decades, resulting in the isolation of a variety of compounds with remarkable electronic structures and properties. Some examples are the singly Lewis-base-stabilised borylenes, wherein boron has a formal oxidation state of +I, and their dimers featuring a boron-boron double bond, namely diborenes. However, no evidence of a Wanzlick-type equilibrium between borylenes and diborenes, which would open a valuable route to the latter compounds, has been found.

Cu-Catalyzed Radical Addition and Oxidation Cascade: Unsymmetrical Trimerization of Indole to Access Isotriazatruxene.

Herein we describe a Cu-catalyzed radical addition and oxidation cascade reaction for the chemo/regioselective synthesis of unsymmetrical indole trimers (isotriazatruxenes, -TATs) from easily available starting materials. The -TATs exhibited blue fluorescence in various solvents with different fluorescence intensities and showed good structural expansibility. A wider range of products could be used in optoelectronic materials by developing suitable derivatives.

Design and synthesis of axially chiral aryl-pyrroloindoles via the strategy of organocatalytic asymmetric (2 + 3) cyclization.

The catalytic asymmetric construction of axially chiral indole-based frameworks is an important area of research due to the unique characteristics of such frameworks. Nevertheless, research in this area is still in its infancy and has some challenges, such as designing and constructing new classes of axially chiral indole-based scaffolds and developing their applications in chiral catalysts, ligands, etc. To overcome these challenges, we present herein the design and atroposelective synthesis of aryl-pyrroloindoles as a new class of axially chiral indole-based scaffolds via the strategy of organocatalytic asymmetric (2 + 3) cyclization between 3-arylindoles and propargylic alcohols.

Catalytic Synthesis of Atropisomeric -Terphenyls with 1,2-Diaxes via Axial-to-Axial Diastereoinduction.

Herein, we report a modular and convergent strategy for the assembly of atropisomeric -terphenyls with 1,2-diaxes via palladium/chiral norbornene cooperative catalysis and axial-to-axial diastereoinduction. Readily available aryl iodides, 2,6-substituted aryl bromides, and potassium aryl trifluoroborates are used as the building blocks, laying the foundation for diversity-oriented synthesis of these scaffolds (46 examples). Other features include the unique axial-to-axial diastereoinduction mode, construction of two axes in a single operation, and step economy.

Regio- and Enantioselective (3+3) Cycloaddition of Nitrones with 2-Indolylmethanols Enabled by Cooperative Organocatalysis.

The regio- and enantioselective (3+3) cycloaddition of nitrones with 2-indolylmethanols was accomplished by the cooperative catalysis of hexafluoroisopropanol (HFIP) and chiral phosphoric acid (CPA). Using this approach, a series of indole-fused six-membered heterocycles were synthesized in high yields (up to 98 %), with excellent enantioselectivities (up to 96 % ee) and exclusive regiospecificity. This approach enabled not only the first organocatalytic asymmetric (3+3) cycloaddition of nitrones but also the first C3-nucleophilic asymmetric (3+3) cycloaddition of 2-indolylmethanols.

NBO/NRT Two-State Theory of Bond-Shift Spectral Excitation.

We show that natural bond orbital (NBO) and natural resonance theory (NRT) analysis methods provide both optimized Lewis-structural bonding descriptors for ground-state electronic properties as well as suitable building blocks for idealized "diabatic" two-state models of the associated spectroscopic excitations. Specifically, in the framework of single-determinant Hartree-Fock or density functional methods for a resonance-stabilized molecule or supramolecular complex, we employ NBO/NRT descriptors of the ground-state determinant to develop a qualitative picture of the associated charge-transfer excitation that dominates the valence region of the electronic spectrum. We illustrate the procedure for the elementary bond shifts of S2-type halide exchange reaction as well as the more complex bond shifts in a series of conjugated cyanine dyes.

Atroposelective Access to Oxindole-Based Axially Chiral Styrenes via the Strategy of Catalytic Kinetic Resolution.

Atroposelective synthesis of axially chiral molecules has attracted substantial attention from chemists because of the importance of such molecules. However, catalytic asymmetric synthesis of axially chiral styrenes or vinyl arenes is underdeveloped and challenging due to the low rotational barrier and weak configurational stability of such molecules. Therefore, the development of powerful strategies for the catalytic atroposelective synthesis of axially chiral styrenes or vinyl arenes is of great importance.

Insights into 2-Indolylmethanol-Involved Cycloadditions: Origins of Regioselectivity and Enantioselectivity.

To gain insights into 2-indolylmethanol-involved reactions and to understand the origins of regioselectivity and enantioselectivity, theoretical investigations on the reaction mechanisms of three representative cycloadditions of 2-indolylmethanols have been carried out. In Ir-catalyzed regioselective (3 + 3) cycloaddition, it was found that the great difference between the energy barriers of the first initiating steps of the two pathways played a key role in determining the observed high regioselectivity and the C3-nucleophilicity of 2-indolylmethanol in this reaction. In chiral phosphoric acid (CPA)-catalyzed regioselective and enantioselective (3 + 3) and (3 + 4) cycloadditions, it was discovered that the great difference between the energy barriers of the transition states corresponding to the ()- and ()-configurations led to the observed high enantioselectivity of the products.

Thermal Conductivity Estimation of Diverse Liquid Aliphatic Oxygen-Containing Organic Compounds Using the Quantitative Structure-Property Relationship Method.

Thermal conductivity is an essential thermodynamic data in chemical engineering applications. Liquid aliphatic oxygen-containing organic compounds are important organic intermediates and raw materials. As a result, estimating thermal conductivity of liquid aliphatic oxygen-containing organic compounds is of significance in industry production.

Recent Advances of Sulfonylation Reactions in Water.

Background: The sulfonyl groups are general structural moieties present in agrochemicals, pharmaceuticals, and natural products. Recently, many efforts have been focused on developing efficient procedures for preparation of organic sulfones.

Materials And Methods: Water, a proton source, is considered one of the most ideal and promising solvents in organic synthesis for its easy availability, low cost, nontoxic and nonflammable characteristics.

Direct cyanation, hydrocyanation, dicyanation and cyanofunctionalization of alkynes.

In this review, direct cyanation, hydrocyanation, dicyanation, cyanofunctionalization and other cyanation reactions of alkynes were highlighted. Firstly, the use of nitriles and development of cyanation was simply introduced. After presenting the natural properties of alkynes, cyanation reactions of alkynes were classified and introduced in detail.

A Strategy for Synthesizing Axially Chiral Naphthyl-Indoles: Catalytic Asymmetric Addition Reactions of Racemic Substrates.

A new strategy for enantioselective synthesis of axially chiral naphthyl-indoles has been established through catalytic asymmetric addition reactions of racemic naphthyl-indoles with bulky electrophiles. Under chiral phosphoric acid catalysis, azodicarboxylates and o-hydroxybenzyl alcohols served as bulky but reactive electrophiles that were attacked by C2-unsubstituted naphthyl-indoles, which underwent a dynamic kinetic resolution to afford two series of axially chiral naphthyl-indoles in good yields (up to 98 %) and high enantioselectivities (up to 98:2 er).

Organocatalytic [4 + 2] cyclizations of para-quinone methide derivatives with isocyanates.

The first [4 + 2] cyclizations of para-quinone methide derivatives with isocyanates have been established under the catalysis of Brønsted acids or Brønsted bases, which efficiently constructed benzoxazin-2-one frameworks in generally high yields (up to 95%). This reaction will not only enrich the research contents of para-quinone methide-involved cyclization reactions but also provide a useful method for constructing biologically important benzoxazin-2-one frameworks.

What Is the Nature of Supramolecular Bonding? Comprehensive NBO/NRT Picture of Halogen and Pnicogen Bonding in RPH···IF/FI Complexes (R = CH, OH, CF, CN, NO).

We employ a variety of natural bond orbital (NBO) and natural resonance theory (NRT) tools to comprehensively investigate the nature of halogen and pnicogen bonding interactions in RPH···IF/FI binary complexes (R = CH, OH, CF, CN, and NO) and the tuning effects of R-substituents. Though such interactions are commonly attributed to "sigma-hole"-type electrostatic effects, we show that they exhibit profound similarities and analogies to the resonance-type 3-center, 4-electron (3c/4e) donor-acceptor interactions of hydrogen bonding, where classical-type "electrostatics" are known to play only a secondary modulating role. The general 3c/4e resonance perspective corresponds to a continuous range of interatomic A···B bond orders (), spanning both the stronger "covalent" interactions of the molecular domain (say, ≥ ½) and the weaker interactions ( ˂ ½, often misleadingly termed "noncovalent") that underlie supramolecular complexation phenomena.

Catalytic Asymmetric (4+3) Cyclizations of In Situ Generated ortho-Quinone Methides with 2-Indolylmethanols.

The first catalytic asymmetric (4+3) cyclization of in situ generated ortho-quinone methides with 2-indolylmethanols has been established, which constructed seven-membered heterocycles in high yields (up to 95 %) and excellent enantioselectivity (up to 98 %). This approach not only represents the first catalytic asymmetric (4+3) cyclization of o-hydroxybenzyl alcohols, but also enabled an unprecedented catalytic asymmetric (4+3) cyclization of 2-indolylmethanols. In addition, a scarcely reported catalytic asymmetric (4+3) cyclization of para-quinone methide derivatives was accomplished.

Design and Catalytic Asymmetric Construction of Axially Chiral 3,3'-Bisindole Skeletons.

The first catalytic asymmetric construction of 3,3'-bisindole skeletons bearing both axial and central chirality has been established by organocatalytic asymmetric addition reactions of 2-substituted 3,3'-bisindoles with 3-indolylmethanols (up to 98 % yield, all >95:5 d.r., >99 % ee).

A theoretical investigation on Cu/Ag/Au bonding in XHP⋯MY(X = H, CH, F, CN, NO; M = Cu, Ag, Au; Y = F, Cl, Br, I) complexes.

Intermolecular interaction of XHP···MY (X = H, CH, F, CN, NO; M = Cu, Ag, Au; Y = F, Cl, Br, I) complexes was investigated by means of an method. The molecular interaction energies are in the order Ag < Cu < Au and increased with the decrease of R. Interaction energies are strengthened when electron-donating substituents X connected to XHP, while electron-withdrawing substituents produce the opposite effect.

Synergistic-Catalysis-Enabled Reaction of 2-Indolymethanols with Oxonium Ylides for the Construction of 3-Indolyl-3-Alkoxy Oxindole Frameworks.

A synergistic-catalysis-enabled reaction of 2-indolymethanols with oxonium ylides has been established that makes use of a three-component reaction between 3-diazooxindoles, alcohols, and 2-indolymethanols under the cooperative catalysis of a metal complex and a Brønsted acid. This reaction has not only provided a new approach for the construction of 3-indolyl-3-alkoxy oxindole scaffolds by utilizing the C3-electrophilicity of an indole, but it is also the first example of a nucleophilic addition of a metal-associated ylide to 2-indolylmethanols. In addition, this reaction also includes a rarely reported trapping of onium ylides with aryl electrophiles.

Synthesis and Fungicidal Activity of 1-(Carbamoylmethyl)-2-aryl-3,1-benzoxazines.

A series of new 1-(carbamoylmethyl)-2-aryl-3,1-benzoxazines were prepared in moderate to good yields by BF₃·OEt₂-catalyzed reactions of aromatic aldehydes with 2-(-substituted carbamoylmethylamino)benzyl alcohols. The structures of the target compounds were confirmed by IR, ¹H-NMR, C-NMR, and elemental analyses. The fungicidal activities of the target compounds against plant fungi were preliminarily evaluated, and some of them exhibited good activity.