An operationally simple electrochemical approach for the one-pot synthesis of quinazolinones employing low-cost and relatively environmentally friendly FeCl3 as electrocatalysts has been established. By use of readily available o-aminobenzamides and alcohols as starting materials, the Fe/acid electrocatalytic system was conducted under mild conditions to provide quinazolinones via indirect anodic oxidation/cyclization/dehydrogenation cascade in moderate to good yields. This protocol provides a practical and environmentally benign route for the preparation of quinazolinone derivatives under mild conditions.

The reaction between aryl diazonium salts and aryl sulphonyl hydrazones in ethanol-pyridine is a simple, metal-free route to the synthesis of 2,5-diaryltetrazoles. However, it is difficult to use for polyaromatic precursors that are poorly soluble in such a polar medium. We show here that the choice of another reaction solvent such as acetone-pyridine can, in many cases, lead to perfect control of the reaction and to the spontaneous precipitation of the targeted tetrazoles.

Aspastipulines and Portulacatone are pyrrolo-azepine containing alkaloids isolated from Asparagus stipularis forssk roots and Portulaca oleracea, respectively that have significant anticancer properties and moderate anti-inflammatory activities. Herein, we report the first total synthesis of five Pyrrolo-azepine containing aspastipuline, portulacatone and related alkaloids from a commercially available starting materials, ethyl 1H-pyrrole-2-carboxylate, via TFAA mediated intramolecular Friedel-Crafts acylation as a key step in concise route with good overall yield.

Seven undescribed diterpenoids paraflexinols A–G (1–7), possessing a fifteen-membered macrocyclic ring, have been isolated from the ethyl acetate extract of the soft coral Paralemnalia thyrosides. The structures of 1–7 have been established by the detailed spectroscopic analysis, including 2D NMR spectroscopy, while their absolute configurations were determined using a modified Mosher's method for 1–3, 6, and 7. For over four decades after the first discovery of the ancestor of these compounds flexibilene (8) from the soft coral Sinularia flexibilis until the current report, no flexibilane-based diterpenoids had been isolated or identified. This study provides detailed NMR data for metabolites of this type for the first time.

A sequential synthetic process was developed to synthesize quinoline/oxindole appended phenylvinyl-2,5-dihydrofuran derivatives. The synthesis involved multiple steps, starting with the base-promoted nucleophilic addition of terminal alkynes to specific carbonyl compounds (11H-indeno[1,2-b]quinolin-11-one and isatin derivatives). The resulting propargyl alcohol derivatives were then subjected to O-allylation. Subsequently, the 1,6-enyne compounds obtained underwent ring-closing enyne metathesis using Grubb's II catalyst, resulting in the desired quinoline/oxindole appended phenylvinyl-2,5-dihydrofuran derivatives. The structures and relative stereochemistry of the synthesized compounds were confirmed by spectroscopic analysis and single-crystal XRD studies.

A novel and efficient palladium-catalyzed direct mono and tetraarylation of tetrathienylethene with various arylbromides to synthesize donor-acceptor system of tetrathienylethene-arene (TTE-Ar) luminophores is reported. The mono- and tetra-arylated TTEs shown an emissive phenomenon, including photoluminescence in various organic solvents and aggregation induced emission (AIE) effect because TTE acts both as an electron-donor for intramolecular charge transfer (ICT) and as activator for AIE. The photoluminescence and AIE of these aryl-substituted TTEs are characterized.

A mild, greener approach via tandem-Michael-cyclization cascade reaction towards the construction of a group of di- and tri-differently substituted indolizine with a broad scope of the substrate is described. The synthetic route to indolizine having different substituents, benzoyl at C5, alkyl/aryl, at C6, and ester at C7 positions is established where different N-alkylated pyrrole-2-carbaldehydes and electron-deficient acetylenes are employed for the synthesis of pyridine moiety. This methodology features water-mediated reactions compatible with various functional groups affording indolizines in good yield without using any oxidant, additive, or catalyst as well. Successfully this methodology has been extended to prepare dicarboxylate and nitrile-substituted indolizines which can be proven important from a biological activity point of view in future.

A series of heterocyclic triaryl methanols were prepared and reacted with enol silyl ethers in the presence of ZnCl2. This reaction gave a variety of functionalized heterocyclic products. A mechanism is proposed involving formation triaryl carbocation electrophiles with delocalization of positive charge to positions in the heterocyclic rings. Nucleophilic attack then occurs at a ring position of the heterocycle.

A mild and efficient one-pot method has been developed for the synthesis of oxime ether derivatives with up to 85% yield by employing tert-butyl nitrite (TBN) as nitrogen source, which occurs under room temperature and exhibits wide substrate scope. The single electron transfer mechanism and the cascade reactions approach have been confirmed.

Helicene-derived 2,2′-bipyridine N-monoxide was evaluated as a Lewis base catalyst for the enantioselective propargylation of N-acylhydrazones with allenyltrichlorosilane. The helicene-derived catalyst provided moderate-to-good reactivity and enantioselectivity for a range of acylhydrazones. This study represents the first example of the catalytic asymmetric propargylation of non-activated acylhydrazones.

An alternative synthesis of 3′-deoxy-3′-fluoro-d-ribofuranosyl nucleoside from d-arabinose is disclosed. Inversion of configuration at C3 on d-arabinoside promoted by DAST reagent is utilized to form lyxo-configured furanoside. After a sequence of fluorination, acidic methanolysis, triflation and displacement by OBz. 3′-deoxy-3′-fluoro-d-ribofuranoside is obtained, which is then transformed to 1-O-benzoyl derivative. The synthesis of three 3′-deoxy-3′-fluoro-d-ribofuranosyl nucleosides, which can be served as fragment of antitumor active cyclic dinucleotide is finally completed through Vorbrüggen glycosylation .

Synthesis of benzo[b]phosphole oxide derivatives having a variety of diverse substituents on the phosphorus atom was achieved by using a corresponding cyclic ethyl phosphinate as a key synthetic intermediate. The photophysical properties of these compounds were found to be dependent upon the electronic nature of the substituents.

For the first time the possibility of regiospecific photocyclization of 3-amido-2-arylbenzofurans was demonstrated. Distinctive feature of the studied photoreaction is involvement of amide function as equivalent of the lateral double bond in aza-1,3,5-hexatriene system for implementation of 6π-electrocyclization. The presented type of photocyclizations is novel and has no analogs in the literature. Based on the presented results the novel approach for the synthesis of benzofuro[3,2-c]isoquinolines was elaborated. The advantages of considered method are easily available starting materials, mild reaction conditions and simple workup procedure without chromatographic purification. The structure of one of benzofuro[3,2-c]isoquinolines was proved by X-ray diffraction.

In this paper we describe the efficient synthesis of d-ribo-phytosphingosine and its analogues commencing from the easily available l-erythrose chiron, which already contained the future C-3 and C-4 stereocentres of our target compounds. Construction of the remaining C-2 stereochemistry relied on aza-Claisen rearrangements to establish the desired vicinal aminoalcohol motif. The aliphatic chain was introduced by means of an olefin cross metathesis process. Completion of this phytosphingolipid synthesis was then achieved through the suitable selection of functional group interconversions, accompanied by selective deprotection protocols. Preliminary in vitro experiments revealed higher antiproliferative activity of the unnatural d-arabino-phytosphingosine 3. HCl in comparison to cisplatin against three of the five cancer cell lines evaluated, with IC50 values ranging from 4.17 μM to 7.63 μM. Moreover, compound 3. HCl has better inhibitory effects on the proliferation of the aforementioned malignant cell lines than its natural stereochemical congener 2. HCl.

Herein, we demonstrate an efficient two-step preparation of substituted cyclobutyl-fused 1-tetralones bearing four contiguous stereochemical centers, including (i) intermolecular aldol condensation of o-cinnamyl acetophenones with arylaldehydes, and (ii) intramolecular photolytic annulation of the resulting o-cinnamyl chalcones. The key structures are determined by single-crystal X-ray analysis. Plausible mechanism is also presented.

Abstract not available

Sulfur-based functional groups are found in a broad range of natural products and therapeutic compounds. The sulfoxide moiety is present in a significant portion of pharmaceuticals, some of them already approved by the FDA, and plays an important role in the therapeutic effects. Sulfoxides are mainly obtained from the oxidation of sulfides but many of the oxidation methodologies suffer from synthetic disadvantages. The disulfide bond has a biological relevance in Nature processes, such as the structure stabilization and aggregation of proteins and can be considered a cleavable linker used in the controlled release of therapeutic drugs and pro-drugs in medicinal chemistry applications. Disulfides can be easily formed by the oxidation of two thiol groups or thiol−disulfide exchange reactions but preparation of non-symmetrical disulfide is not an easy task. The sulfenic acid function constitutes an unusual source of sulfoxides and disulfides, in reactions that almost always require only heating. This review covers the work that has been done on the synthesis of sulfoxides and disulfides via sulfenic acid intermediacy and the applications that this chemistry offers in the biological and medical field and in materials science.

Methyl itaconate–anthracene adducts (MIAs) were previously introduced as chiral derivatizing agents (CDAs) for the determination of chiral secondary alcohols. In this study, they were further employed with chiral primary amines to assign their absolute configuration. Each chiral amine compound was linked to the (R)- and (S)-MIAs through amidation to obtain diastereomeric amides in moderate yield. The modified Mosher's method was applied, where the difference in chemical shift (ΔδSR = δHS−MIA-amide – δHR−MIA-amide) values of each substituent of the chiral amine adducts was utilized to validate the capability of MIAs as CDAs. Finally, the proposed model was successfully achieved, and the MIAs were proven effective for the determination of the absolute configuration of chiral amines.

Cross-dimerization reactions that employ nonequivalent 9-fluorenones have been accomplished. This cross-dimerization doesn't employ any additives such as metals and salts, that was unthinkable heretofore. Because the cross-couplings were achieved by phosphite solvent alone, they were not only operationally simple but also productively efficient owing to suppression of homo-dimerization. Significantly, the resulting single spiroketones were transformed into a hexacycle core of dibenzo[g,p]chrysene having twofold tert-butyl groups and twofold halogen atoms. The synthesis of solution-processable and multi-tunable hexacycle, coupled with the mechanistic aspects, enables general access to non-planar polyarenes from the viewpoint of diversity-oriented synthesis.

The first chemo- and regioselective one-pot convergent synthesis of 2H-1,3-thiazin-4(3H)-ones has been successfully realized employing β-ketothioamides and alkyne derivatives of N-hydroxyphthalimide (NHPI)-ester under mild conditions in good to excellent yields. The process is triggered by the in-situ generation of dienolate intermediate followed by intramolecular selective N-cyclization. Remarkably, metal- and additive-free conditions, an open atmosphere, non-hazardous reagents, and easy purification are added characteristics to this cascade [3 + 3] annulative strategy. This heteroannulative approach will not only provide an effective method to access various 1,3-thiazin-4-ones but also augment the research domain of thioamides.