HETEROCYCLES

■ Contents

■ Recent Development of Stereoselective Glycosylation Reactions

Shino Manabe*

*Laboratory of Functional Molecule Chemistry, Pharmaceutical Department and Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo, 142-8501, Japan

Abstract

Carbohydrates are the most abundant class among biological molecules. Advances in glycobiology have revealed the vital roles played by glycosides and glycoconjugates in biological events. In this context, access to homogenous oligosaccharides and glycoconjugates is critical for various biological investigations. Glycosylation is the cornerstone of glycoside synthesis, and during glycosylation, the control of stereoselectivity at the anomeric position is highly important. In this review, recent progresses in 1,2-cis-glycosylation reactions are summarized, with a focus on the influence of the protecting groups on the conformations of the glycosyl donors, role of reaction mixture additives, and synthetic utility of endocyclic cleavage of glycoside. Development of robust glycosylation reaction will contribute to biologically active oligosaccharide synthesis.

■ An Overview of Quantitative and Qualitative Approaches on the Synthesis of Heterocyclic Kojic Acid Scaffolds through the Multi-Component Reactions

Fatemeh Mohajer and Ghodsi Mohammadi Ziarani*

*Department of Chemistry, Alzahra University, Vanak Square, 1993893973, Tehran, Iran

Abstract

Multi-component reactions as powerful synthetic methods were developed to provide efficient complex scaffolds, including kojic acid, through the one-pot one-step fashion. This review highlights the progress of multicomponent reactions covering kojic acid under different conditions through, short reaction time, higher yields, and environmental friendliness via producing various molecules. The aim of this paper is to review the literature from 2015 to 2020 via quantitative and qualitative approaches.

■ Synthesis of Poly(cyclotriphosphazene-co-3,3'-sulfonyldianilide) Microspheres and Their Adsorption of Anionic (Congo Red) Dye

Zeng Xiong, Yanfei Wang,* Xiaoqing Xie, Honzheng Li, and Chen Yao

*School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001 PR China

Abstract

The cyclomatrix phosphazenes-co-3,3'-sulfonyldianiline PSD-NH2 microspheres with active amino groups on the surface were prepared by precipitation which was used to removal organic dyes from aqueous solution. The synthesized amino cyclomatrix phosphazenes (PSD-NH2) microspheres were characterized by FT-IR, SEM, XPS and XRD. The effects of different pH, sorbent dosage, contact time, initial Congo red (CR) concentration and different temperature on the adsorption of Congo red by the cross-linked microspheres were studied. The experimental data show that the adsorption capacity of PSD-NH2 microspheres on Congo red reaches 186.70 mg/g under the optimal adsorption conditions. It conforms to the pseudo-second-order kinetic equation and Langmuir isotherm model. The selective adsorption mechanism for Congo red dye can be summarized as intermolecular electrostatic interaction, hydrogen bond between PSD-NH2 microspheres adsorbed on the surface and Congo red, π-π and C-H…π stacking and other molecular forces. Thermodynamic studies have shown that the adsorption of Congo redon PSD-NH2 microspheres is endothermic and spontaneous in nature. Thus, amino polyphosphazene (PSD-NH2) microspheres have excellent adsorptionperformance for Congo red.

■ Synthesis of Roche Lactone via the Enantioselective Alcoholysis of meso-Cyclic Anhydride Strategy: A Practical Approach Employing an Efficient and Reusable Organic Microgel Auxiliaries

Fei Xiong,* Chang-Cheng Xi, Chao Ma, Lu Chen, Ming-Wei Sun, Xing-Guang Zhang, and Dan-Feng Hong

*Department of Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China

Abstract

Roche lactone, a key chiral intermediate of the natural water-soluble B series vitamin (+)-biotin, was synthesized from meso-cyclic anhydride in overall yield 78% through three steps, including heterogeneous asymmetric desymmetrization, chemoselective reduction and lactonization.

■ [2+2]Photocycloaddition of 5,6-Substituted 2-Oxo-2H-pyran-3-carboxylates with Alkenes

Yun-Han Hsieh, Hiroki Iwasaki, Yumina Iwai, Miki Adachi, Kanako Kitai, Eri Kuribayashi, Yuri Hirata, Suzuna Sakaguchi, Naoko Sakaguchi, Naoto Kojima, and Masayuki Yamashita*

*Kyoto Pharmaceutical University, 1 Misasagi-Shichono-cho, Yamashina, Kyoto 607-8412, Japan

Abstract

The [2+2]photocycloaddition of alkenes and 5,6-substituted 2-oxo-2H-pyran-3-carboxylates with an ester as an electron-withdrawing group was developed. The 3,4-adducts, 4,5-disubstituted 3-oxa-2-oxobicyclo[4.2.0]oct-4-ene-1-carboxylates, were obtained in moderate yields accompanied by considerable amounts of the 5,6-adducts, 1,6-disubstituted 2-oxa-3-oxobicyclo[4.2.0]oct-4-ene-4-carboxylates. These structures, including their stereochemistry, were determined by various spectral and computational analyses, and some were examined by X-ray crystallographic analysis. The determined regio- and stereoselectivities were explained by frontier orbital theory.

■ Synthesis of Some (Triindolyl)dimethanes and (Tetraindolyl)trimethanes

Kittya Somphol, Naresh Kumar, and David StC. Black*

*School of Chemistry, The University of New South Wales, Sydney 2052, Australia

Abstract

Acid catalyzed substitution reactions of 3-substituted-4,6-dimethoxyindole-2,7-dimethanols with 4,6-dimethoxyindoles substituted at C3 and C7 give (triindolyl)dimethanes with 2,2’- and 2,7’-methylene links in good yields. A related example involving a 4,6-dimethoxyindole substituted at C3 and C2 generates the corresponding (triindolyl)dimethane with 2,7’- and 7,7’-methylene links. Similar reactions of 2,7-di(hydroxymethyl)-4,6-dimethoxy-3-methylindole occur with N-methylindole and in the case of 1,2-di(indolyl-1-methyl)benzene generate a 16-membered ring compound in high yield. This methodology was also applied to (diindolyl)-dimethanols to afford a range of tetraindolyl trimethanes.

■ Synthesis and Biological Studies of Some New Pyrazole, Dihydropyridinethione, Pyrimidine, Thiophene and 4H-Pyran Derivatives

Ibrahim Saad Abdel Hafiz, Mohamed Ahmed Mahmoud Abdel Reheim,* Hala Mohamed Reffat, and Ahmed Adel Mohamed Sarhan

*Department of Chemistry, Faculty of Science, Arish Univeristy, Arish 45511, Egypt

Abstract

This study aims to synthesis of 1-(2-hydroxy-4-methylphenyl)-3-phenylpropane-1,3-dione 3 in a quantitative yield from the reaction of ethyl benzoylacetate and m-cresol using a microwave in the absence of solvents. Phenylpropane-1,3-dione derivative 3 was used as the key synthetic intermediate for the synthesis of many derivatives in this study. A new pyrazole 12, pyrimidine 15, thiophene 37, 4H-pyrane 51 and pyridine derivatives 8, 28, 34, 41 and 46 were synthesized through different chemical reactions. The structures of the newly synthesized compounds were confirmed based on analytical and spectral data. The compounds were evaluated for both their in vitro antibacterial and antifungal activities. The compounds showed varying degree of antimicrobial activity.

■ Synthesis of α-Bromomethyl Ketones in CuBr - bpy System

Abulipizi Gulizhabaier, Hasimujiang Balat, and Abulikemu Abudu Rexit*

*Xinjiang Key Laboratory of Energy Storage and Photoelectrocatalytic Materials and Department of Chemistry, Xinjiang Normal University, Urumqi, China

Abstract

Herein we reported a convenient, regiospecific, efficient and fairly general method for the preparation of α-bromomethyl ketones from α,α,α-tribromomethyl carbinols with 2.2 equivalents of copper(I) bromide and 2,2'-bipyridine in refluxing 1,2-dichloroethane.

■ Peniphilones A and B: Azaphilone Alkaloids from the Endophytic Fungus Penicillium maximae

Yuhei Koyanagi, Yuki Hitora, Teppei Kawahara, and Sachiko Tsukamoto*

*Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan

Abstract

Two new azaphilone alkaloids, peniphilones A and B (1 and 2), and a known congener, (+)-sclerotiorin (3), were isolated from the endophytic fungus Penicillium maximae by screening based on chemical analysis by UPLC-HRMS with our in-house extract library of natural sources. The structures of 1 and 2 were elucidated on the basis of NMR and HRESI-MS spectroscopic data.