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Inclusion crystals were formed from ketones with aromatic diimide-based macrocycles possessing adamantane units, where the oxygen atoms of guests interacted with the electron-deficient π-surfaces of the aromatic diimides through CO⋯π contacts.

Inclusion crystals containing several halocarbons were formed by three types of diimide-based macrocycles. Iodomethane was encapsulated within the cavity of the macrocycle through halogen-related interactions.

Adamantane-based macrocycles with pyrazine or tetrazine units afforded porous crystals with distinct surface properties of 1D pores, which captured multiple water molecules from the air or liquid water in a single-crystal-to-single-crystal fashion.

Neighboring group participation involving a 6-membered ring structure is rare, despite the privilege of 6-membered ring transition structures in organic chemistry. We examined the putative role of a 6-membered cyclic intermediate with neighboring group participation of nitrogen cation in

We studied the Z/E preference of N-phenylthioacetamide (thioacetanilide) derivatives in various solvents by means of 1H NMR spectroscopy, as well as molecular dynamics (MD) and other computational analyses. Our experimental results indicate that the Z/E isomer preference of secondary (NH)thioamides of N-phenylthioacetamides shows substantial solvent dependency, whereas the corresponding amides do not show solvent dependency of the Z/E isomer ratios. Detailed study of the solvent effects based on molecular dynamics simulations revealed that there are two main modes of hydrogen (H)-bond formation between solvent and (NH)thioacetamide, which influence the Z/E isomer preference of (NH)thioamides. DFT calculations of NH-thioamide in the presence of one or two explicit solvent molecules in the continuum solvent model can effectively mimic the solvation by multiple solvent molecules surrounding the thioamide in MD simulations and shed light on the precise nature of the interactions between thioamide and solvent. Orbital interaction analysis showed that, counterintuitively, the Z/E preference of NH-thioacetamides is mainly determined by steric repulsion, while that of sterically congested N-methylthioacetamides is mainly determined by thioamide conjugation.

From the leaves of Ardisia quinquegona, two alkylated tetronic acid derivatives, named ardisiatetrons A and B (1, 2), and four triterpenoids (3–6) were isolated together with one known compound (7) by a combination of various kinds of chromatography. The structure of new methyl migrated triterpene (3) was confirmed by X-ray crystallographic analysis. Compounds 2, 3, and 7 showed moderate anti-Leishmania activity and cytotoxicity towards A549 cells.

An adamantane-bearing macrocycle showed permanent intrinsic porosity and adsorption of small organic compounds in a single-crystal-to-single-crystal fashion. Guest uptake by the porous crystals gave rise to the structural transformation of the supramolecular organic framework, resulting in the change of shape and size of one-dimensional pores.

Halogen⋯halogen contacts are considerably important intermolecular interactions. An adamantane-based macrocycle with pyridazine moieties (1) was synthesized from 3,6-dichloropyridazine and disubstituted adamantane possessing chlorophenol moieties in 57% yield as a new host molecule. The crystallization of 1 in various solvents afforded six inclusion crystals. The macrocyclic framework had a nearly hexagonal structure with a cavity, and was assembled into various network structures composed of layer architectures bearing channels. In crystals containing cyclic ethers, halogen⋯halogen interactions between all chlorine atoms of 1 were observed. Meanwhile, in crystals containing halomethanes and aromatic compounds, CH⋯Cl interactions alternately and partially appeared.

A methylene- and adamantane-bridged macrocycle with four biphenyl units (1) was synthesized as a host molecule. The vapor diffusion of n-hexane into a chloroform solution of 1 afforded a co-inclusion crystal (1a) containing both guests, which was confirmed by X-ray crystallographic analysis. In the case of the other four hexane isomers, a crystal (1b) containing only one chloroform molecule was obtained, indicating the selective inclusion of n-hexane from among the five hexane isomers. When n-heptane or n-pentane instead of n-hexane was employed as an alkane guest, crystal 1b or guest-free crystal 1c was formed, showing that the macrocycle recognizes the length of the alkyl chain. Furthermore, when dichloromethane was used instead of chloroform, crystal 1d with only a dichloromethane guest was generated, showing that chloroform is essential for the accommodation of n-hexane into the crystals.

This work reports that cyclophanes and their [2]catenanes were synthesized by the SN Ar reactions of disubstituted adamantanes bearing halophenol units and 3,6-dichlorotetrazine in moderate yields. In the crystalline state, the cyclophanes had hexagonal structures with a cavity. The [2]catenanes were composed of two macrocycles that were singly interlocked and orthogonally arranged, indicating the construction from eight component molecules through eight C-O bonds in a one-step reaction in up to 33 % yield. The cyclophanes were assembled to afford a supramolecular organic framework in the solid state, which exhibited permanent intrinsic porosity and adsorption of leaf alcohol or aldehyde in a single-crystal to single-crystal fashion. The molecular structures of the liquid guests were determined by single-crystal X-ray analysis. The formation of catenanes and the use of cyclophane-based porous crystals in the crystalline sponge method may be largely ascribed to the solvophobic effects and the van der Waals interactions that originate in the aliphatic and bulky nature of the adamantane units.

Disubstituted adamantanes having pyrogallol derivatives as V-shaped host molecules were synthesized to prepare complexes with carboranes, which are representative spherical guest molecules for macrocyclic compounds, including calixarenes and cyclotriveratrylenes. The crystallization of o-carborane (a) and 1,3-bis(3,4,5-trimethoxyphenyl)adamantane (1) in toluene resulted in the formation of inclusion crystals (1a) in a 1 : 1 ratio. X-ray crystallographic analysis revealed that two oxygen atoms in 1 interact with two hydrogen atoms of a through CH⋯O interactions to afford the complexes. In the case of 1,3-bis(3,4,5-triethoxyphenyl)adamantane (2), no inclusion crystal was obtained due to steric hindrance of the ethyl groups. Furthermore, the crystallization of 1 and a benzoquinone derivative (b) provided reddish crystals (1b) with a 1 : 2 host : guest complexation stoichiometry, where lone pair⋯π interactions in the complexes were observed in addition to donor–acceptor interactions.

A macrocycle having benzophenone-3,3′,4,4′-tetracarboxylic diimide and adamantane units (1) was synthesized from benzophenone-3,3′,4,4′-tetracarboxylic dianhydride and 1,3-adamantanedimethanamine in 37% yield. The crystallization of 1 and 1,4-dioxane (a) in chloroform resulted in the formation of inclusion crystal (1a), and the stoichiometric ratio of 1, chloroform, and a was 1 : 2 : 1. The host molecules were arranged to afford network structures with one-dimensional channels in the crystalline state, in which two different guest molecules were jointly accommodated through CH⋯O and CH⋯Cl interactions. Inclusion crystals containing cyclic ethers (b–d) with the same stoichiometric ratio were obtained under identical conditions. In all of the inclusion crystals, the shape and conformation of 1 and their arrangements were similar to those of crystal 1a, and the molecular structures of the liquid guests were characterized.

A simple method for the synthesis of monoselenides and diselenides having 1,2,3-triazole ring is described herein. The three component reaction of ethynylstibanes, organic azides, and selenium powder is catalyzed by CuI (10 mol%) using 1,10-phenanthroline as the ligand (10 mol%) under aerobic conditions. Either selenides or diselenides can be synthesized by selecting the appropriate amount of selenium powder for otherwise identical reaction conditions. The obtained selenides and diselenides having a 1,2,3-triazole ring are all novel compounds. By using an antimony reagent, this one-pot reaction provides regioselective double Se-arylation under simple reaction conditions.

We studied the

From the leaves of Ardisia quinquegona, two alkylated tetronic acid derivatives, named ardisiatetrons A and B (1, 2), and four triterpenoids (3-6) were isolated together with one known compound (7) by a combination of various kinds of chromatography. The structure of new methyl migrated triterpene (3) was confirmed by X-ray crystallographic analysis. Compounds 2, 3, and 7 showed moderate anti-Leishmania activity and cytotoxicity towards A549 cells.

The expectation that antimony (Sb) compounds should display phosphorescence emissions based on the “heavy element effect” prompted our interest in the introduction of antimony to a biaryl as the bridging atom in a fused heterole system. Herein, the synthesis, molecular structures, and optical properties of novel benzene-fused heteroacenes containing antimony or arsenic atoms are described. The stiboles and arsole were prepared by the condensation of dibromo(phenyl)stibane or dichloro(phenyl)arsine with dilithium intermediates derived from the corresponding dibromo compounds. Nuclear magnetic resonance (NMR) spectroscopy and X-ray crystal analysis revealed that the linear pentacyclic stibole was highly symmetric in both the solution and crystal states. In contrast, the curved pentacyclic stibole adopted a helical structure in solution, and surprisingly, only M helical molecules were crystallized from the racemate. All synthesized compounds produced very weak or no emissions at room temperature or in the solid state. In contrast, the linear penta- and tetracyclic stiboles exhibited clear phosphorescence emissions in the CHCl3 frozen matrix at 77 K under aerobic conditions.

A disubstituted adamantane derivative bearing chloropyrimidine units (1) was synthesized as an acyclic host molecule to construct guest-inclusion crystalline materials, and the molecular structures of these crystalline materials were determined by X-ray crystallographic analysis. The crystallization of 1 and trans-decahydronaphthalene (a) in chloroform afforded co-crystal (1a) with 2 : 1 host : guest complexation stoichiometry. The guest molecule was accommodated within the cavity of the cyclic dimers of 1 built from Cl⋯π interactions between the chloropyrimidine units. These complexes were assembled into network structures through intermolecular interactions. From the Hirshfeld surface analysis and the 2D fingerprint plot of a in co-crystal 1a, the maximum contribution is from the H⋯H contacts between 1 and a, indicating that the main driving force for the guest inclusion is dispersive force. Co-crystals containing cycloalkanes and cycloalkenes (b–f) and having the same stoichiometry were obtained under identical conditions. In all the co-crystals, the shapes and sizes of the cyclic dimers and the molecular networks were similar to those of crystal 1a, and the molecular structures of the guests were characterized.

Hydrogen-bonding compound (1), which is composed of p-terphenyl and adamantanecarboxylic acid, acted as a host molecule for three amides, respectively, forming crystals. Crystals containing the amides (1a and 1b) were produced from N,N-dimethylformamide (DMF) and N,N-diethylformamide (DEF) in 1:2 host:guest complexation stoichiometry, respectively, whereas guest-free crystals (1c) were generated from N-methylformamide (NMF). In the crystal structures of 1a and 1b, carboxylic acids of 1 interact with oxygen atoms of the amide guests through hydrogen bonds to afford network and layer architectures. Crystals 1a and 1b were given from equimolar binary mixtures of DMF or DEF and NMF, respectively. Further, from a mixture of DMF and DEF, guest-inclusion crystals 1d different from 1a and 1b were formed, where DMF was preferentially accommodated. Competition experiments revealed that the selectivity order of 1 for the amide guests was DMF > DEF ≫ NMF.

From the leaves of Diospyros maritima, collected from Okinawa Island, eight new glycosides based on ent-kaurane-type diterpenoids, entitled diosmariosides A-H, were isolated. The absolute structure of diosmarioside E (5) was determined by X-ray crystallographic analysis. The structure of diosmarioside H was elucidated to be a dimeric compound between diosmarioside A and a sugeroside through a ketal bond. An assay of cytotoxicity towards the lung adenocarcinoma (A549) cell line was performed. Among the compounds isolated, only diosmarioside D (4) and sugeroside 9 showed strong activity. The anti-microbial activity toward multi-drug resistant strains was also determined, but no activity was observed.

The separation of p-xylene from a mixture of four C8 alkylaromatics has been realized through a highly selective inclusion by an acyclic host molecule (1) via crystallization. In the crystal structure, the guest molecule was included in the cavity of the cyclic dimer of 1. Further, the host molecule specifically discriminated p-xylene from a mixture of eight C8 and C9 aromatic compounds.

This work reports that cyclophanes and their [2]catenanes were synthesized by the S

The synthesis of benzimidazo[2,1-b]benzoselenoazoles is described. The novel ring-closure reaction of 1-(2-bromoaryl)benzimidazoles with Se powder is promoted by Cs2CO3 (2 equiv) in DMF at 150 °C. Moreover, the obtained tetracyclic heterocycles are all novel compounds. Single-crystal X-ray analysis of the parent benzimidazo[2,1-b]benzoselenoazole revealed that the tetracyclic ring is almost planar. Absorption spectroscopy data of the benzimidazo[2,1-b]benzoselenoazoles showed the λmax was dependent on the number of rings.

1,3-Oxazepines are of interest because of their application as biologically active substances. Herein, 2′-amino-2-hydroxybiphenyl was reacted with isothiocyanate-derived thioureas and treated in situ with iodine in the presence of triethylamine to afford dibenzo[d,f][1,3]oxazepine derivatives in good-to-excellent yields. X-ray analysis revealed that the obtained product comprises a 7-membered heterocycle and has a Z-configuration imine moiety in its solid state. All oxazepine derivatives obtained by this reaction are novel compounds.

The Pd-catalyzed cross-coupling reactions of Sb-aryl-1,5-azastibocines with alkenes are described. The reactions of azastibocines with alkenes such as vinyl ketones, alkenes, and acrylates in the presence of 10 mol% PdCl2 at 80 °C in DMA under aerobic conditions produced Heck adducts in moderate-to-excellent yields. Single-crystal X-ray and NMR analysis revealed that the aryl donors in this reaction, the Sb-aryl-1,5-azastibocines, are hypervalent compounds that display N–Sb intramolecular non-bonding interaction. These are the first examples of Pd-catalyzed Heck-type arylations using heterocyclic hypervalent organoantimony compounds. Although the reactions proceeded efficiently with the azastibocines, they hardly progressed with trivalent and pentavalent triarylantimony reagents.

A disubstituted adamantane derivative having chloropyrimidine units (1) was utilized as a V-shaped host molecule to create inclusion crystals and to elucidate the molecular structures of the guests by X-ray crystallographic analysis. The crystallization of 1 and 1,3,5,7-cyclooctatetraene (a) in chloroform resulted in the formation of co-crystal (1a) with 2:3 host:guest complexation stoichiometry. Host 1 was assembled into a molecular network composed of double layer structures bearing channels where guest molecules (a) were accommodated. Co-crystals (1b, 1c) containing 1,3-cyclooctadiene (b) and 1,5-cyclooctadiene (c) were obtained at identical stoichiometry under similar conditions. The host molecules arrangement in both 1b and 1c was similar to that of 1a. In each case, guest molecules b and c were accommodated in the channels formed between the layers of the host molecules. In all co-crystals, the molecular structures of the guests a‒c, along with the host frameworks, were determined by crystallographic analysis.

From the leaves of Diospyros maritima, collected from Okinawa Island, eight new glycosides based on ent-kaurane-type diterpenoids, entitled diosmariosides A-H, were isolated. The absolute structure of diosmarioside E (5) was determined by X-ray crystallographic analysis. The structure of diosmarioside H was elucidated to be a dimeric compound between diosmarioside A and a sugeroside through a ketal bond. An assay of cytotoxicity towards the lung adenocarcinoma (A549) cell line was performed. Among the compounds isolated, only diosmarioside D (4) and sugeroside 9 showed strong activity. The anti-microbial activity toward multi-drug resistant strains was also determined, but no activity was observed.

Disubstituted adamantane derivative possessing chloropyrazine (1) was synthesized and used as an extended V-shaped host molecule for the preparation of inclusion crystals containing hexyne isomers. The crystallization of 1 with 3-hexyne or 2-hexyne in chloroform provided co-crystals (1a, 1b) with 1:2 host:guest complexation stoichiometry, whereas guest-free crystals (1c) were produced in the case of 1-hexyne. In the co-crystals, the dimers built from 1 through CH···O interaction were arranged into a molecular network through multiple intermolecular interactions, and the guest molecules were accommodated within the cavity built from four molecules of 1. From the crystallization of equimolar binary mixtures of 3-hexyne or 2-hexyne and 1-hexyne in the presence of 1, co-crystals 1a and 1b were supplied, respectively. Competition experiments revealed that the selectivity order of 1 for the hexyne isomers was 3-hexyne and 2-hexyne ≫ 1-hexyne.

Methanol extracts of the rhizomes or fruit of Amomum celsum Lamxay & M.F. Newman (Zingiberaceae) yielded 5 compounds one of which, 1,3 S,5 S-trihydroxy-1-(4-hydroxyphenylethyl)cyclohexane (2), is new and one, 4-hydroxybibenzyl (1), is reported as a natural product for the first time. In addition, 3 known compounds, 5-hydroxy-3,7,3′,4′-tetramethoxyflavone (3), 3,5-diacetoxy-1,7- bis(3,4-dihydroxyphenyl)heptane (4), and 1,4-hydroquinone (5), were also isolated. Their structures were determined by performing extensive analysis of high-resolution electrospray ionization-mass spectrometry and nuclear magnetic resonance spectroscopic data. The absolute configuration of 2 was unambiguously established by X-ray crystallography and Mosher’s method. Cytotoxicity of compounds 1 and 2 against MCF-7 and Hep-G2 human cancer cell lines were tested in the sulforhodamine B cytotoxic assay. A plausible biosynthesis of 1 and 2 in A. celsum was proposed.