Synthesis of Ibuprofen Conjugates with Betulin,Allobetulin, and Betulinic Acid

Chemistry of Natural Compounds - Syntheses of mono- and diester derivatives of betulin, allobetulin, and betulinic acid with ibuprofen that were based on Steglich condensation or acid-chloride...     

Synthesis of Allobetulin, 28-Oxyallobetulin and Related Biomarkers from Betulin and Betulinic Acid Catalysed by Solid Acids

Betulin (1a) is an abundant natural product in the birch bark. Betulin itself currently has little usage. However, allobetulin (2a) has been used as an important intermediate in the further transformation of triterpenoids and as a sample for biological studies.¹ For example, allobetulin was further transformed to a highly active antifeedant for heliothis zea larvae. Some biomarkers (3a,b; 4a,b) with the same or similar structure as ring-E of 2a were identified in a brown coal.³ Consequently, the conversion of 1a to synthetically, biologically and geochemically more important 2a is of great significance. The transformation of 1a to 2a was reported as early as 1922 by Schulze et al in which betulin was isomerized by formic acid, involving formation and hydrolysis of allobetulin formate, to give 2a in moderate yield.⁴     

A Concise Approach to the Synthesis of Carnosic Acid Type Diterpenes

AIDS has seriously affected human being's health and about 13.9 million people have been killed by AIDS in the world. So far, A. Paris et al1 found that Carnosic acid and its analogs posses inhibitory effect on HIV-1 protease and HIV virus replication activity. In order to clarify the structure-active relationship of this kind of compounds, a concise approach was designed, which is a convergent synthesis. Best to our knowledge, it is the first successful convergent route in total synthes…     

A Concise Approach to the Synthesis of L-and D-Deoxyribose

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A Concise Synthesis of (R)-GABOB from L-Malic Acid

A concise synthesis of (R)-4-amino-3-hydroxybutanoic acid, starting from L-malic acid, is reported. The approach is based on the conversion of the oxazolidin-2-one 9 into a full protected form of (®)-GABOB by an Arndt-Eistert reaction.     

TLC Determination of Betulinic Acid from Nymphodies macrospermum: A New Botanical Source for Tagara

The accepted botanical source of Tagara, an ayurvedic drug is Valeriana jatamansi Jones. In South India, a drug by the name of Granthika Tagara is used as Tagara in several therapeutic preparations. Currently, no analytical procedures appear to be available for quality control purposes. A sensitive, selective and precise thin-layer chromatographic method has been developed and validated for the analysis of betulinic acid in Nymphoides macrospermum. Separation and quantification was achieved by TLC using ternary mobile phase of hexane:ethyl acetate:acetic acid (7:3:0.03, v/v) (R _F 0.60) on precoated silica gel 60F₂₅₄ aluminium plates and densitometric determination was carried out after derivatization with anisaldehyde-sulphuric acid reagent in the reflection/absorption mode at 540 nm. The calibration curve was linear in the concentration range of 100–600 ng spot^?1. The method was validated for precision, repeatability and accuracy. The proposed method was found to be simple, precise, specific, sensitive and accurate for the quantification of betulinic acid. This is the first TLC report for the identification and quantification of betulinic acid in N. macrospermum and may be useful for the routine quality control of Granthika Tagara.     

Kinetics of Polycondensation of Betulin with Adipic Acid

The influence of various factors on the kinetics of polycondensation of betulin (a triterpene alcohol of the lupane series) with adipic acid was studied.     

A Review on Preparation of Betulinic Acid and Its Biological Activities

Betulinic acid, a pentacyclic triterpene, is distributed in a variety of plants, such as birch, eucalyptus and plane trees. It shows a wide spectrum of biological and pharmacological properties, such as anti-inflammatory, antibacterial, antiviral, antidiabetic, antimalarial, anti-HIV and antitumor effects. Among them, the antitumor activity of betulinic acid has been extensively studied. However, obtaining betulinic acid from natural resources can no longer meet the needs of medicine and nutrition, so methods such as chemical synthesis and microbial biotransformation have also been used to prepare betulinic acid. At the same time, with the development of synthetic biology and genetic engineering, and the elucidation of the biosynthetic pathways of terpenoid, the biosynthesis of betulinic acid has also been extensively researched. This article reviews the preparation of betulinic acid and its pharmacological activities, in order to provide a reference for the research and utilization of betulinic acid.     

Concise Synthesis of Ximenynic Acid

Abstract

An improved synthesis of ximenynic acid (1) starting from castor oil has been developed with the direct chlorination of ricinstearolic acid as the key step. By this modification, the synthetic route was more concise and economic. The separation of geometric somers was achieved by repeated urea fractionation.

Supplemental materials are available for this article. Go the publisher's online edition of Synthetic Communications to view the free supplemental file.     

Allylic Hydroxylation Through Acid Catalysed Epoxy Ring Opening of Betulinic Acid Derivatives

Acid catalysed epoxy ring opening of several lupane type triterpenoids leads to unusual allylic hydroxylation. The reaction involves the formation of epoxide by m‐chloroperbenzoic acid followed by the treatment of mineral acid. The simple methodology finds utility to introduce a hydroxyl function at the allylic position in these triterpenoids, which is otherwise quite difficult.     

Methods of Betulin Extraction from Birch Bark

Betulin is the most popular of the known triterpenoids of the lupan series. It has valuable pharmacological properties. It exhibits antibacterial, antiviral, antitumor, hypolipidemic and other types of activity. The prospects of using betulin in medicine, pharmacology, and veterinary medicine require the development of effective methods for obtaining it from waste from the woodworking industry. Therefore, the question arises of the need to develop a technology for isolating and purifying triterpenoids from birch bark in large quantities. This review contains a variety of methods for the isolation of betulin. The advantages and disadvantages of the proposed methods are described. The following methods are considered: vacuum sublimation after preliminary alkaline; vacuum pyrolysis; supercritical extraction with carbon dioxide or mixtures of carbon dioxide with various solvents; extraction with organic solvents. Also, the method of microwave is described, it is activation on the example of the Kyrgyz birch (Betula kirghisorum), this is an endemic species that has not been studied before, growing on the territory of the Republic of Kazakhstan.     

A Concise Synthetic Method for Constructing 3-Substituted Piperazine-2-Acetic Acid Esters from 1,2-Diamines

We report a short synthetic route for synthesizing 2,3-substituted piperazine acetic acid esters. Optically pure amino acids were efficiently converted into 1,2-diamines that could be utilized to deliver the title 2,3-substituted piperazines in five steps with a high enantiomeric purity. The novel route facilitated, for the first time, the synthesis of 3-phenyl substituted-2-piperazine acetic acid esters that were difficult to achieve using other methods; however, in this case, the products underwent racemization.     

A Concise Route to the Strongylophorines

An efficient eight‐step semisynthesis of strongylophorine‐2 from the abundant building block isocupressic acid is reported. The route represents the first synthetic entry into this class of natural products and provides access to six additional family members. A novel iron(III)‐mediated rearrangement–cyclization cascade and a directed photochemical sp³ C?H δ‐lactonization are the key transformations that enable concise assembly of these bioactive polycyclic meroterpenoids.     

A Concise Route to Valacyclovir Hydrochloride

An efficient and concise synthesis of valacyclovir hydrochloride ( 4 ), which is a prodrug of acyclovir ( 3 ) is described. The synthesis was accomplished in two stages by coupling acyclovir with (2S)‐2‐azido‐3‐methylbutanoic acid followed by reduction (Scheme 2).     

A Concise Route to (+)-Estrone

A concise route to the Torgov diene, the key intermediate of estrone, has been devised using a chiral dioxycyclopentenone as the starting material by employing a sequence of five steps of reactions involving a Lewis acid-mediated Diels-Alder reaction with Dane's diene.     

Concise Synthesis of Pentenyl Phenyl Acrylic Acid

Pentenyl phenyl acrylic acid is a structural unit of pepticinnamin E, a natural product and a bisubstrate inhibitor of FPTase. In this article, a new synthetic strategy was developed to prepare pentenyl phenyl acrylic acid with high stereoselectivity and high overall yield of 78.6%. The method used in producing these effects involved the application of a five‐step procedure. Pentenyl phenyl acrylic acid was synthesized starting from 2‐iodo‐benzyl alcohol through an E‐selective Wittig–Horner reaction, and then the Sonogashira reaction was used to produce 2‐(1‐pentynyl)‐E‐ethyl‐cinnamoylate, which was quantitatively hydrogenated, catalyzed by Lindlar catalyst.     

Concise Approach to T-Shaped NBN-Phenalene Cored Luminogens as Intensive Blue Light Emitters

Small organic molecules with finely tunable physical properties are highly desired for the fabrication of low-cost and high-performance organic electronic devices. In this work, the syntheses of a series of T-shaped NBN-embedded dibenzophenalene derivatives through the formation of a key brominated intermediate in a stoichiometrically controlled reaction are presented. The geometric and electronic structures of these T-shaped molecules can be simply tailored by attaching substituents along the direction perpendicular to the molecular main backbones, resulting in desirable physical properties, such as high thermal stability with a decomposition temperature of more than 350 °C, and intensive blue luminescence with a quantum yield up to 0.62. Organic light-emitting diode devices fabricated with such molecules as the emitting layer release pure blue light with CIE (0.16, 0.12).