A Facile Synthesis of Various Butenolides

The synthesis of α'-acyloxy-α,β-unsaturated cyclic ketones from the corresponding α,β-unsaturated cyclic ketones by using manganese (III) acetate in combination with 2-chloropropionic acid followed by subsequent Arbuzov and intramolecular Horner-Emmons cyclization reactions provided a convenient synthetic pathway to various butenolides 4a-d.     

A Preparative Synthesis of D,L-Gabaculine

The γ-aminobutyric acid-α-ketoglutaric acid transaminase inhibitor, gabaculine (1) was first isolated as an optically active amorphous powder from a culture filtrate of streptomyces toyacaenis subspecies 1039 by Mishima and co-workers in 1976¹. The structure (1) was assigned on the basis of physical and chemical data and has been confirmed by two total syntheses of the racemic compound^1,2.     

An Optimized Synthesis of 2-Methoxyestradiol,A Naturally Occurring Human Metabolite with Anticancer Activity

2-Methoxyestradiol, a naturally occurring human metabolite with demonstrated anticancer activity, has been synthesized in three steps and 76% yield from the bis(MOM) ether of 2-formylestradiol.     

Divergent Total Synthesis of Fornicin A,Fornicin D,and Ganodercin D,Meroterpenoids from Ganoderma Mushrooms

The meroterpenoids fornicin A, fornicin D, and ganodercin D, found in mushrooms of the Ganoderma genus, have been prepared in a concise and divergent synthesis route. The characteristic unsaturated γ-ketoacid moiety was obtained via an optimized step-wise aldol condensation between two readily accessible building blocks. THP-protection of a phenolic hydroxyl group under basic conditions was developed, a protocol that adds to the versatility of this protecting group.     

Synthesis of xyloketal A, B, C, D, and G analogues

A series of demethyl analogues of the natural products xyloketal A, B, C, D, and G have been prepared in a notably direct manner from 3-hydroxymethyl-2-methyl-4,5-dihydrofuran and a series of corresponding phenols. These syntheses featured a boron trifluoride diethyl etherate-promoted electrophilic aromatic substitution reaction as a key step. In the case of the synthesis of analogues of xyloketal A, the process was found to be highly efficient (up to 93% yield). The optimized isolated yield of these reaction products is remarkable in view of the fact that this transformation involves, minimally, six individual reactions. Moreover, these synthetic studies provide significant insight into the possible biogenic origin of the xyloketal natural products.     

A Short Synthesis of Clionamine D

Herein we describe a scalable four‐step preparation of α‐methylene‐γ‐lactone 3 from steroidal sapogenin. This method allowed a facile synthesis of clionamine D, a natural aminosteroid with potent autophagy bioactivity and unprecedented chemical structure.     

Trimetallic Chalcogenide Species: Synthesis,Structures, and Bonding

In an attempt to isolate boron-containing tri-niobium polychalcogenide species, we have carried out prolonged thermolysis reactions of [Cp*NbCl₄] (Cp* = ɳ⁵-C₅Me₅) with four equivalents of Li[BH₂E₃] (E = Se or S). In the case of the heavier chalcogen (Se), the reaction led to the isolation of the tri-niobium cubane-like cluster [(NbCp*)₃(μ₃-Se)₃(BH)(μ-Se)₃] (1) and the homocubane-like cluster [(NbCp*)₃(μ₃-Se)₃(μ-Se)₃(BH)(μ-Se)] (2). Interestingly, the tri-niobium framework of 1 stabilizes a selenaborate {Se₃BH}⁻ ligand. A selenium atom is further introduced between boron and one of the selenium atoms of 1 to yield cluster 2. On the other hand, the reaction with the sulfur-containing borate adduct [LiBH₂S₃] afforded the trimetallic clusters [(NbCp*)₃(μ-S)₄{μ-S₂(BH)}] (3) and [(NbCp*)₃(μ-S)₄{μ-S₂(S)}] (4). Both clusters 3 and 4 have an Nb₃S₆ core, which further stabilizes {BH} and mono-sulfur units, respectively, through bi-chalcogen coordination. All of these species were characterized by ¹¹B{¹H}, ¹H, and ¹³C{¹H} NMR spectroscopy, mass spectrometry, infrared (IR) spectroscopy, and single-crystal X-ray crystallography. Moreover, theoretical investigations revealed that the triangular Nb₃ framework is aromatic in nature and plays a vital role in the stabilization of the borate, borane, and chalcogen units.     

Study on the Synthesis of Metabolite CM2 of Clausenamide

Synthesis of the optically active metabolite of clausenamide cm2(3,5-dihydroxy-5-(α-hydroxylbenzyl)-1-methyl-4-benzylpyrrolidin-2-one)from 3-O-acetyl-clausenamide was described.     

Synthesis,Fluorescence and Electrochemistry of a New ECL-active Species

Recently, there has been much interest in electrochemiluminescence (ECL) generated from tris (2,2 -bipyridine) ruthenium (II) because of its application in iinmmunoassay, nucleic acid hybridization assay, and detection of other important chemical, biochemical, and biological substances. ECL is a technique by which a chemiluminescent reaction is generated from reagents produced in the vicinity of an electrode surface when a potential is applied.     

Reliable Synthesis of Various Nucleoside Diphosphate Glycopyranoses

A reliable and high yielding synthetic pathway for the synthesis of the biologically highly important class of nucleoside diphosphate sugars (NDP‐sugars) was developed by using various cycloSal‐nucleotides 1 and 9 as active ester building blocks. The reaction with anomerically pure pyranosyl‐1‐phosphates 2 led to the target NDP‐sugars 20 – 45 in a nucleophilic displacement reaction, which cleaves the cycloSal moiety in anomerically pure forms. As nucleosides cytidine, uridine, thymidine, adenosine, 2′‐deoxy‐guanosine and 2′,3′‐dideoxy‐2′,3′‐didehydrothymidine were used while the phosphates of D ‐glucose, D ‐galactose, D ‐mannose, D ‐NAc‐glucosamine, D ‐NAc‐galactosamine, D ‐fucose, L ‐fucose as well as 6‐deoxy‐D ‐gulose were introduced.     

Polymer-Supported Synthesis of Various Pteridinones and Pyrimidodiazepinones

In this report, we employed the solid-phase synthetic approach to prepare variously substituted dihydropteridinones, tetrahydropyrrolopteridinones, and pyrimidodiazepinones, using a versatile building block-4,6-dichloro-5-nitropyrimidine. All these compounds are pharmacologically significant scaffolds of the great importance of medicinal chemists. The fast and efficient synthetic methodology is highly desirable for defining their structure-activity relationship (SAR) and optimizing pharmacokinetic properties. Our research efforts utilize simple synthetic methods to generate a library of analogues for future SAR studies. The efficiency of our approach was exemplified in various pteridinones as well as pyrimidodiazepinones.     

Azides in the Synthesis of Various Heterocycles

In this review, we focus on some interesting and recent examples of various applications of organic azides such as their intermolecular or intramolecular, under thermal, catalyzed, or noncatalyzed reaction conditions. The aforementioned reactions in the aim to prepare basic five-, six-, organometallic heterocyclic-membered systems and/or their fused analogs. This review article also provides a report on the developed methods describing the synthesis of various heterocycles from organic azides, especially those reported in recent papers (till 2020). At the outset, this review groups the synthetic methods of organic azides into different categories. Secondly, the review deals with the functionality of the azido group in chemical reactions. This is followed by a major section on the following: (1) the synthetic tools of various heterocycles from the corresponding organic azides by one-pot domino reaction; (2) the utility of the chosen catalysts in the chemoselectivity favoring C−H and C-N bonds; (3) one-pot procedures (i.e., Ugi four-component reaction); (4) nucleophilic addition, such as Aza-Michael addition; (5) cycloaddition reactions, such as [3+2] cycloaddition; (6) mixed addition/cyclization/oxygen; and (7) insertion reaction of C-H amination. The review also includes the synthetic procedures of fused heterocycles, such as quinazoline derivatives and organometal heterocycles (i.e., phosphorus-, boron- and aluminum-containing heterocycles). Due to many references that have dealt with the reactions of azides in heterocyclic synthesis (currently more than 32,000), we selected according to generality and timeliness. This is considered a recent review that focuses on selected interesting examples of various heterocycles from the mechanistic aspects of organic azides.     

Synthesis of ZnO Photocatalysts Using Various Surfactants

Russian Journal of Physical Chemistry A - Zinc oxide (ZnO) nanostructured materials have received significant attention because of their unique physicochemical and electronic properties. In...     

氯硝西泮及其代谢产物7-氨基氯硝西泮的化学合成

以2-氰基-4-硝基苯胺为原料,经氧化偶联、酰胺化、亲核取代反应、分子内Wittig反应、还原反应等过程实现了7-氨基氯硝西泮的化学合成,在反应完成后可以直接过滤淋洗即可得到产物,无需其他纯化,操作简便。