Synthesis of (+)-lycoricidine by the application of oxidative and regioselective ring-opening of aziridines

A highly stereoselective total synthesis of (+)-lycoricidine has been described. The salient features of this synthesis are the one-pot elimination followed by allylation reaction, ring-closing metathesis, stereoselective aziridine formation, Dess-Martin periodinane, and silica gel mediated oxidative ring-opening of aziridine to form alpha,beta-unsaturated ketone (allyl amine) and intramolecular Heck cyclization.

Iodine-catalyzed highly diastereoselective synthesis of trans-2,6-disubstituted-3,4-dihydropyrans: application to concise construction of C28-C37 bicyclic core of (+)-sorangicin A

A novel iodine-catalyzed highly diastereoselective synthesis of trans-2,6-disubstituted-3,4-dihydropyrans have been achieved from delta-hydroxy alpha,beta-unsaturated aldehydes by treating with allyltrimethyl silane in THF at room temperature with good to excellent yields. This methodology has been successfully implemented for a concise asymmetric synthesis of C28-C37 dioxabicyclo[3.2.1]octane ring system of (+)-sorangicin A in 8 steps with 21% overall yield.

4-N-pyridin-2-yl-benzamide nanotubes compatible with mouse stem cell and oral delivery in Drosophila

p-aminobenzoic acid (PABA), a structural moiety of many commercial drugs, is self-assembled with linker alkyl side chains to form tubular nanostructures. The tubes exhibited fluorescence either intrinsic or from fluorescent molecules embedded in the wall during self-assembly. Uptake and inter-cellular delivery of the conjugated nanotubes in human cancer cells and in mouse embryonic stem cells were demonstrated by fluorescence imaging and flow cytometry. Biocompatibility, cytotoxicity and clearance were monitored both ex vivo in mouse multipotent embryonic stem cells and in vivo in adult Drosophila. Accumulation of nanotubes had no adverse effects and abnormalities on stem cell morphology and proliferation rate. A distinct distribution of two separate nanotubes in various internal organs of Drosophila interprets that accumulation of nanomaterials might be interdependent on the side chain modifications and physiological settings of cell or tissue types. Unlike carbon nanomaterials, exposure of PABA nanotubes does not produce any hazards including locomotion defects and mortality of adult flies. Despite differential uptake and clearance from multiple live tissues, the use of self-assembled nanotubes can add new dimensions and scope to the development of dual-purpose oral carriers for the fulfilment of many biological promises.

Synthesis of (3R,5R)-harzialactone A and its (3R,5S)-isomer

The total synthesis of (3R,5R)-harzialactone A (1) and its (3R,5S)-isomer (2) is described. Epoxide opening with thioacetal and diastereoselective reductions are used as key reactions.

Bismuth-triflate-catalyzed Prins–Ritter reaction — An efficient synthesis of 4-amidotetrahydropyrans

Bismuth(III) triflate is found to be an effective Lewis acid in catalyzing a three-component reaction of homoallylic alcohol, carbonyl compound, and nitrile at ambient temperature via the Prins–Ritter sequence to furnish 4-amidotetrahydropyrans in high yields, all with cis selectivity. Spirocyclic 4-amidotetrahydropyrans are obtained in case of cyclic ketones.Key words: Prins cyclization, bismuth(III) triflate, homoallyl alcohol, 4-amidotetrahydropyrans.

Three-component reaction of aldose sugars, aryl amines, and 1,3-diones: a novel synthesis of annulated pyrroles

Aldose sugars undergo smooth coupling with enamines, generated in situ from aryl amines and 1,3-diketones, in the presence of 10 mol % of InCl3 in water at 80 degrees C to furnish annulated pyrrole derivatives in relatively good to high yields. The use of InCl3, in combination with water, makes this procedure quite simple, more convenient, and environmentally friendly.

Bismuth(III)-catalyzed rapid and highly efficient synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles in water

2-Aryl-1-arylmethyl-1H-benzimidazoles are prepared in high yields under extremely mild conditions via the condensation of aryl-1,2-diamines with aromatic aldehydes using 10 mol% of bismuth triflate in water. The use of water and readily available bismuth triflate makes this process quite simple, more convenient, and environment-friendly.Key words: aryl-1,2-diamines, aromatic aldehydes, bismuth catalysis, benzimidazoles.

Synthesis and cellular uptake of cell delivering 2,6-pyridinediylbisalkanamide submicron-sized sheets in hela cells

2,6-Pyridinediylbisalkanamides were synthesized, using diaminopyridine (DAP) as a linker and alkyl chains of varying lengths, that upon self-assembly form submicron-sized sheets and their uptake into the cytoplasm of HeLa cells was studied by confocal microscopy.

Stereoselective Formal Total Synthesis of (+)-Methynolide

A highly stereoselective and convergent formal total synthesis of (+)-methynolide is described. The salient features of this synthesis have been the construction of the C1-C7 and C8-C11fragments via a desymmetrization approach, Sharpless asymmetric epoxidation of an allyl alcohol, respectively, and linkage of both the fragments by Nozaki-Hiyama-Kishi reaction.

Iodine-promoted Prins-cyclization of ketones — A facile synthesis of spirocyclic-4-iodo-tetrahydropyrans and 5,6-dihydro-2H-pyrans

Homoallylic and homopropargylic alcohols undergo smooth coupling with ketones in the presence of molecular iodine at ambient temperature to produce spirocyclic-4-iodotetrahydropyrans and 5,6-dihydro-2H-pyrans, respectively, in high yields in a short reaction time with high selectivity. The use of molecular iodine makes this procedure quite simple, more convenient, and cost-effective.Key words: Prins-cyclization, iodine, homopropargylic alcohol, spirocyclic-4-iodopyrans.

Behavioral response of the borer beetle Hoplocerambyx spinicornis to volatile compounds of the tree Shorea robusta

Essential oils isolated from leaves (LO), bast (BO), heartwood (HO), and ethereal extract of resin (EER) of Shorea robusta were bioassayed with electroantennograph (EAG) and wind tunnel to study the behavioral response of male and female beetles, Hoplocerambyx spinicornis Newm., the most injurious heartwood borer of the tree. LO, BO, HO, and EER were shown to exhibit the electrophysiological activity in the female beetle, while LO and BO in the male beetle. In wind-tunnel studies, only BO elicited the attractant activity to both the sexes. A possible correlation of the constituents of the BO identified by GC/MS with the bioactivity is also presented.

Differentiation of diastereomeric conduramine derivatives under electron ionization and chemical ionization mass spectral conditions

Diastereomeric conduramine derivatives, i.e., (1R,2S,3R/S,6S)-6-(N-carbomethoxyamino) 1,2-O-isopropylidenecyclohex-4-ene-1,2,3-triol (1 and 2) and their O-acetyl derivatives (3 and 4), were studied using gas chromatography (GC) with electron ionization (EI) and chemical ionization (CI). The EI mass spectra of diastereomeric pairs show consistent differences in the relative abundances of characteristic ions. The EI fragmentation patterns are based on precursor/product ion spectra, high-resolution mass spectrometry (HRMS) and deuterium labelling. The CI spectra show differences from the EI spectra, and the isobutane/CI spectra are much simpler than the methane/CI spectra. The differences shown in the CI spectra are similar to those shown in the product ion spectra of [M+H](+) ions generated under electrospray ionization (ESI) conditions. Theoretical calculations are performed to understand the observed differences. The differences in the relative stabilities of molecular ions, or protonated molecules at different sites, can explain the observed differences in the spectra.