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Origanum onites L., known as Turkish oregano, has great traditional, medicinal, preservative, and commercial importance. It is used for the treatment of several kinds of ailments, such as gastrointestinal disorders, diabetes, high cholesterol, leukemia, bronchitis, etc. In this review, traditional use, phytochemistry, and pharmacology of O. onites reported between 1988 and 2014 were discussed. This review was prepared based on literature survey on scientific journals and books from libraries and electronic sources, such as Web of Science, PubMed, Scopus, Google Scholar, etc. All databases were searched up to June 2014. Several different classes of terpenoids, triterpene acids, phenolic acids, hydroquinones, flavonoids, hydrocarbons, sterols, pigments, fatty acids, tocopherols, and inorganic compounds were detected mainly in the aerial parts of this plant. Pharmacological studies revealed that extracts obtained from several solvents and individual compounds exhibited antimicrobial, antiviral, antioxidant, insecticidal, anticancer, hepatoprotective, genotoxic, antidiabetic, cholinesterase inhibitory, anti-inflammatory, analgesic activities, etc. O. onites, in general, exhibited remarkable activity potential in almost all test systems. The results of toxicity studies indicated that O. onites did not show any significant toxicity and mutagenicity on Drosophila and Salmonella. Toxicity of the extracts/essential oils and also individual compounds should be evaluated on mammalian cells to ensure their safety. The bioactivity of individual compounds aside from terpenoids should also be assessed in detail. Additionally, mode of action for the bioactive compounds should be evaluated to understand the complex pharmacological effects of these phytochemicals.

The hydroxyamination reagent Br-N-(CO2Me)2 underwent Markovnikov addition to various olefins in the presence of catalytic BF3·OEt2 and provides efficient access to aminoalcohols. The reaction provided the trans-1-bromo, 2-N-bis-carbamate adduct stereoisomer in all cases. The resulting adduct underwent cyclization to give an oxazolidinone, which could be readily hydrolyzed to an oxazolidin-2-one or an amino alcohol.

Reaction of trans-4,5-diaryl-2-imidazolines with aliphatic and aromatic aldehydes is accompanied by decarboxylation to yield cis-4,5-diaryl-2-imidazolines (III) after oxidation of the intermediate alcohols.

A simple, convenient, regio- and stereoselective method to prepare 2-imidazolines is reported.

We describe herein a convenient method for the synthesis of 1,2,4-triazolines using oxazolones and azodicarboxylates. Subsequent treatment of these 1,2,4-triazolines with NaOH provides efficient access to the corresponding triazoles.

A series of novel C11-substituted derivatives of azaelliptitoxin (azatoxin) have been synthesized and tested for their inhibitory activity against human DNA topoisomerase II. Incorporation of a C11 polyamine or amine resulted in an increase in the intercalation properties of the drug and a decrease of topoisomerase II activity. The structure-activity relationship (SAR) profile of the nonintercalating C11 anilino azatoxin class follows the SAR of the (anilino)acridine family. 11-(4-Cyanoanilino)azatoxin (14) was found to be the most active analog in this series, exhibiting approximately 10-fold higher activity than azatoxin 12 and etoposide.

The acute hepatotoxicity displayed by the pyrrolizidine alkaloids, which obviates their clinical utility, is a result of activation in vivo by cytochrome P450 mediated oxidation. Now the first reductively activated progenitor of the highly cytotoxic dehydropyrrolizidine alkaloid dehydromonocrotaline has been synthesized and demonstrated to mediate interstrand DNA cross-link formation (see scheme); pyrrolizidine alkaloids exert their cytotoxicity through the formation of DNA-DNA interstrand and DNA-protein cross-links.

The first intermolecular Friedel−Crafts acylation of a variety of aromatic substrates with azetidinones is described. The Friedel−Crafts acylations are performed under very mild conditions, using trifluoromethanesulfonic acid to produce β-amino aromatic ketones in excellent yields.

The natural product hymenialdisine was first isolated in 1980 from the marine sponges of the genera Hymeniacidon, Acanthella, Axinella and Pseudaxinyssa. The structure was elucidated on the basis of X-ray crystallography demonstrating a structurally interesting pyrrole-azepin-8-one ring system bonded to a glycocyamidine ring. Great interest has been taken in synthesizing this type of scaffold due to its potent activity in competitive kinase inhibition. In addition, several patents have claimed pharmacological use of these compounds for prevention and treatment of different diseases. The challenging syntheses of hymenialdisine and its analogues are described in this review as well as their evaluation as kinase inhibitors.

Reactions that create a quaternary stereocenter offer a wealth of synthetic utility and are often needed to provide access to the structural diversity of stereocenters found in natural products and biologically important molecules. We have developed a new 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI)-mediated oxazole rearrangement that affords quaternary 5,5-(aryl, allyl)-substituted hydantoins found in many biologically significant compounds. Furthermore, these quaternary hydantoins can be chemically manipulated to yield the corresponding quaternary imidazolones, which is a unique scaffold found in a compound from the tunicate Dendrodoa grossularia. Herein, we report the scope of this novel rearrangement and the proposed mechanism and showcase its utility through the total synthesis of a marine alkaloid from D. grossularia and two analogues.

Quaternary α-amino acids play vital roles in protein and synthetic chemistries. Stereoselective access to such molecules has been an intensive focus of research in recent years, and new methods are continuously being explored. The present mini-review gives an overview of stereoselective syntheses of quaternary α-amino acids produced from racemic oxazolones.

We report herein a racemic key intermediate in the synthesis of salinosporamide A via a tert -alkyl amino hydroxy carboxylic ester produced in an ene-type reaction of an oxazolone with an enol ether.

A short synthesis of an indole marine alkaloid (1) from the tunicate Dendrodoa grossularia is described. The key step in the synthesis involves a novel twist on an underutilized oxazole rearrangement, which produces the quaternary stereocenter in the molecule.

tert-Alkyl amino hydroxy carboxylic acids are abundantly present within the structure of many biologically active natural products. We describe herein the synthesis of these substrates using an oxazolone-mediated ene-type reaction with enol ethers followed by NaBH4 reduction of the intermediate oxazolone.

We report herein an intermolecular ene reaction using oxazolones with enol ethers which results in the formation of novel quaternary amino esters in near quantitative yields. The overall reaction transformation closely resembles an intermolecular version of the Conia-ene reaction. The reactions are uncatalyzed and occur under very mild conditions.

[reaction: see text] We report herein a trimethylsilyl chloride mediated substrate controlled 1,3-dipolar cycloaddition for the diastereoselective synthesis of either syn- or anti-imidazolines. This method provides scaffolds with four points of diversity and control over two stereocenters.

[reaction: see text] We report herein a one-pot synthesis of 2,4,5-trisubstituted oxazoles via a Friedel-Crafts/Robinson-Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted oxazoles in good yields.

We report herein a silver(I)-catalyzed exo-selective synthesis of highly substituted Δ1-pyrroline scaffolds from amino acid-derived munchnones. Silver acetate successfully catalyzed the cycloaddition reaction of azlactones with alkenes, generating Δ1-pyrrolines in very good yields without isomerization to the Δ2-pyrrolines or decarboxylation.

A diastereoselective multicomponent synthesis of highly functionalized imidazolines is reported. A silicon mediated 1,3 dipolar cycloaddition of the in situ generated munchnone with an imine resulted in the formation ofhighly substituted imidazolines. The imidazolines contain a four-point diversity and two stereocenters and the cycloaddition reaction is applicable to aryl, alkyl, acyl, and heterocyclic substitutions.

We report here a highly diastereoselective multicomponent synthesis of imidazolines. These low molecular weight scaffolds contain a four-point diversity applicable to alkyl, aryl, acyl, and hetereocyclic substitutions. [structure: see text]