Structure and stereochemistry of boschniakine, boschnialactone, and boschnialinic acid, an oxidation product of boschnialactone

The applications of catalytic asymmetric halocyclization in natural product synthesis

Catalytic asymmetric halocyclization of olefinic substrate has evolved rapidly and been well utilized as a practical strategy for constructing enantioenriched cyclic skeletons in natural product synthesis.

Total syntheses of several iridolactones and the putative structure of noriridoid scholarein A: an intramolecular Pauson-Khand reaction based one-stop synthetic solution

A simple and general approach towards the total syntheses of several iridolactones such as (±)-boschnialactone, (±)-7-epi-boschnialactone, (±)-teucriumlactone, (±)-iridomyrmecin, (±)-isoboonein, (±)-7-epi-argyol, (±)-scabrol A, (±)-7-epi-scabrol A, and (±)-patriscabrol as well as the putative structure of scholarein A is delineated. The synthetic strategy features a diastereoselective intramolecular Pauson-Khand reaction (IPKR) to construct the iridoid framework followed by some strategic synthetic manipulations to access the targeted monoterpenes including those having diverse oxy-functionalization patterns and with 3-5 contiguous stereogenic centres in a highly stereocontrolled manner. Also, the present endeavour includes the first total synthesis of scabrol A.

The genus Boschniakia in China: An ethnopharmacological and phytochemical review

ETHNOPHARMACOLOGICAL RELEVANCE

As a group of important medicine plants, Boschniakia rossica (Cham. et Schltdl) Fedtsch. and B. himalaica Hook．f．et Thoms, which are the only two species in the genus Boschniakia (Orobanchaceae), have long been used in traditional Chinese medicine for their multiple therapeutic uses related to enhanced renal function, erectile dysfunction, defaecate and hepatoprotective. Additionally, the two species are also used as dietary supplements in wine, cosmetics, and other healthy food.

AIM OF THE REVIEW

By providing comprehensive information and data of genus Boschniakia on botany, traditional medicinal uses, phytochemistry, pharmacological research and toxicology, this review aims to summary the group of natural compounds from Boschniakia discovered so far. The other aims are to reference research findings of their biological activities and functions in medicine, physiology, and cell biology to highlight the compound candidates which can be used for further drug discovery in several pharmaceutical areas including antioxidation, anticancer, anti-inflammation, anti-senile, and immunology.

MATERIALS AND METHODS

All of the available information on B. rossica and B. himalaica was collected from the electronic resources (such as PubMed, SciFinder Scholar, CNKI, TPL (www.theplantlist.org), Google Scholar, Baidu Scholar, and Web of Science).

RESULTS

After a comprehensive analysis of the literatures from available online sources, the results show that both species of genus Boschniakia are valuable and popular herbal medicines with potentials to cure various ailments. The phytochemical studies revealed that the chemical compositions of this genus were mainly iridoid glycosides and phenylpropanoid glycosides. To date, 112 compounds have been isolated from the genus, while their crude extracts and purified compounds have been found to possess a wide range of biological activities including anti-senile, antitumor and anticancer, anti-inflammatory, protecting liver, boost memory, anti-oxidation, anti-lipid peroxidative, and antiviral activities.

CONCLUSIONS

The existing traditional uses of the genus Boschniakia have been evaluated, and the properties of the genus are summarized based on botany, phytochemistry, pharmacological research, and toxicology. This review aims to introduce the utilization and application of the genus Boschniakia to modern drug discovery, traditional medicinal plant utilization, herbal species conservation, and the development of medicinal and health-maintaining products.

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part II: Iridomyrmecins

Following our earlier approach to the synthesis of dihydronepetalactones, all eight stereoisomers of trans-fused iridomyrmecins were synthesized starting from the enantiomers of limonene. Combined gas chromatography and mass spectrometry including enantioselective gas chromatography revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain (4S,4aR,7S,7aR)-iridomyrmecin of 95–97% ee and stereochemically pure (4S,4aS,7R,7aS)-iridomyrmecin as a minor component.

A novel iridoid from Boschniakia rossica

A novel iridoid, (4R)-4-hydroxymethylboschnialactone (1), has been isolated from Boschniakia rossica, together with three previously known compounds, (24S)-3beta-hydroxy-24-ethylcholest-5-en-7-one (2), (24R)-3beta-hydroxy-24-ethylcholest-5-en-7-one (3) and methyl p-coumarate, using column chromatography. The structures of compounds were elucidated by spectroscopic methods.

Catalyst-controlled inverse-electron-demand hetero-Diels-Alder reactions in the enantio- and diastereoselective synthesis of iridoid natural products

[reaction: see text] Iridoid natural products 1-4 are accessed stereoselectively by means of tridentate (Schiff base)Cr(III)-catalyzed hetero-Diels-Alder reactions between ethyl vinyl ether and enantioenriched 5-methyl-1-cyclopentene-1-carboxaldehyde. An efficient route to the aldehyde from citronellal is afforded by the ring-closing metathesis reaction.

Catalytic Asymmetric Iodocarbocyclization Reaction of 4-Alkenylmalonates and Its Application to Enantiotopic Group Selective Reaction

The iodocarbocyclization reaction of 4-alkenylmalonate derivatives proceeded with excellent enantioselectivity (>/=95% ee) in the presence of 10-40 mol % of Ti(TADDOLate)(2). The Ti(TADDOLate)(2)-mediated catalytic asymmetric reaction was extended to the enantiotopic group selective reaction of bisalkenylated malonates, giving rise to trisubstituted cyclopentanoid compounds with both high diastereoselectivity (86-94% de) and excellent enantioselectivity (>/=95% ee). An efficient synthesis of (+)-boschnialactone from the product of the present reaction was also achieved.