Asymmetric Total Synthesis of (+)- and (-)-Myrioneurinol Employing a "Resolutive" Late-Stage Barton-McCombie Deoxygenation.

The so-called Barton-McCombie reaction is a transformation commonly used in organic synthesis for promoting deoxygenation of alcohols. Almost 50 years after its discovery, this reaction has become a powerful tool for organic chemists due to its wide range of applicability and functional group tolerance, which allows, with high level of anticipation, its incorporation into complex synthetic routes such as the ones aiming at the total synthesis of natural products. In this article, we describe the first example of a resolutive version of this reaction by using a chiral chlorothionoformate as the activating reagent, and its related strategic potential through a late-stage application to the total synthesis of both enantiomers of myrioneurinol, a complex tetracyclic alkaloid featuring 5 contiguous stereogenic centers.

Harnessing the Power of an Extensive EMS-Induced Sorghum Population for Rapid Crop Improvement.

Plant breeders leverage mutagenesis using chemical, biological, and physical mutagens to create novel trait variations. Many widely used sorghum genotypes have a narrow genetic base, which hinders improvements using classical breeding. Enhancing the diversity of the sorghum genome thus remains a key priority for sorghum breeders.

Asymmetric Allenylation of Alkynes mediated by Chiral Organoselenated Reagents under Oxidative Conditions.

The reactivity of novel chiral lactamide-substituted diselenide-based reagents under oxidative conditions was exploited to develop a metal-free method for the preparation of enantioenriched allenylamides from simple alkynes in good yields, and with enantiomeric excesses up to 99 %. The key of the success in this method is attributed to the hydrogen-bonded lactamide appendages that ensure configurational stability of chiral vinyl selenoxide intermediates for an optimal enantiotopic β-syn-elimination step.

Novel benzoxazinone derivative as potent human neutrophil elastase inhibitor: Potential implications in lung injury.

Neutrophil elastase, a powerful physiological defence tool, may serve as drug target for diverse diseases due to its bystander effect on host cells like chronic obstructive pulmonary disease (COPD). Here, we synthesised seven novel benzoxazinone derivatives and identified that these synthetic compounds are human neutrophil elastase inhibitor that was demonstrated by enzyme substrate kinetic assay. One such compound, PD05, emerged as the most potent inhibitor with lower IC as compared to control drug sivelestat.

Studies directed toward the synthesis of hedycoropyrans: total synthesis of des-hydroxy (-)-hedycoropyran B (-rhoiptelol B).

A full account of our efforts directed towards the synthesis of the diarylheptanoid-derived natural products hedycoropyrans that led to the total synthesis of -rhoiptelol B is described. In this endeavor, we have attempted two distinct synthetic strategies to access hedycoropyrans A and B, which led us to establish a facile synthetic route for des-hydroxy (-)-hedycoropyran B (-rhoiptelol B) from simple and readily accessible building blocks of 4-allylanisole and vanillin, employing Sharpless asymmetric epoxidation, CBS reduction, and an intramolecular AgOTf-catalyzed oxa-Michael reaction of suitably functionalized hydroxy-ynone as key transformations. The investigations disclosed herein will provide insights into designing novel synthetic routes for THP-DAH-derived natural products.

Fe(III)-Catalyzed Diastereoselective Friedel-Crafts Alkylation-Hemiketalization-Lactonization Cascade for the Synthesis of Polycyclic Bridged 2-Chromanol Lactones.

An unprecedented Fe(III)-catalyzed Friedel-Crafts alkylation-hemiketalization-lactonization cascade of electron-rich hydroxy arenes and distinctively functionalized unsaturated 4-keto esters is developed for the construction of polycyclic bridged 2-chromanol lactones. Following this simple and facile protocol, a broad range of products was prepared in good to excellent yields as a single diastereomer. An unusual conglomerate (enantiomerically pure polymorph) of 3ac is reported along with the absolute stereochemistry, and the remaining products were rigorously confirmed by single-crystal X-ray analysis and analogy.

Intramolecular oxyacetoxylation of N-allylamides: an expeditious synthesis of oxazolines and oxazines by using a PhI(OAc)/hydrogen fluoride-pyridine system.

The synthesis of oxazolines and oxazines from N-allylamides was accomplished via an unprecedented reaction set. This reaction involved an intramolecular cyclization of N-allylamides resulting from nucleophilic attack of the allylamine on the benzoxazin-4-one. Unlike the previous literature, the isolable N-allylamide could readily be subjected to exo and endo fashion ring-closure under conditions to afford the title compounds.