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A one-pot and sequential Ugi/SNCsp2 four-component reaction was introduced for the synthesis of cycloalkene-fused [1,4]thiazepine derivatives. A variety of cyclic β-bromovinyl aldehyde with different sizes, amines, and isocyanides were reacted with thioglycolic acid. This approach can provide a practical and rapid access to the fused bioactive cycloalkene structures containing thiazepine, and peptide unit, which proved the achievement of a significant structural diversity. Further use of this method has been successfully applied in synthesizing a variety of quinoline-fused [1,4]thiazepines with satisfactory results. The practical nature of this approach was demonstrated by a gram-scale synthesis of a selected product.

A tandem one-pot strategy for the synthesis of 4-iodo-3-aryl(alkyl)-1H-pyrano[4,3-b]quinolin-1-ones and (E)-3-(iodo(phenyl)methylene)isobenzofuran-1-(3H)-ones from 2-alkynylhydrazones has been developed through oxidation and regioselective 6-endo- and 5-exo-iodocyclization pathways by using NIS as an iodinating reagent. This approach tolerates a variety of in situ generated alkynyl-containing tosylhydrazones and affords the corresponding products in high yields. The protocol has also been applied for the synthesis of different derivatives in good to excellent yields.

First reported by Joseph Bunnet et al., base-catalyzed halogen dance reaction has puzzled chemists for decades, to come up with new ideas regarding the mechanism of this chemical reaction. A series of deprotonation followed by fast metal-halogen exchanges are among the most recent mechanisms reported so far. Using density functional theory, DFT, computations and focused on the Bunnet type isomerization halogen dance reactions of iodobenzene derivatives, iodo-bridged transition state, TS, are proposed. The new TS is then used to lay out 8 possible isomerization and 18 possible disproportionation paths. The possible mechanistic pathways are then carefully analyzed based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. These mechanistic pathways, sketch a comprehensive pattern for base-catalyzed halogen dance. There is still a lot to study in the chemistry of poly halogenated aryls.

Bis(imidazolium) chlorides based on 1,2-phenylenediamine were introduced as efficient ligand precursors in the Pd-catalyzed Mizoroki-Heck cross-coupling reactions of substituted aryl halides with activated alkenes to afford the corresponding functionalized alkenes. While high to excellent yields (78–96%) were obtained with aryl bromides, moderate yields (51–59%) were achieved for aryl chlorides in this protocol.

Ever since the halogen dance reaction was discovered by Bunnet et al, synthetic chemists have utilized the transformation in many desirable ways to build substituted heterocyclic target molecules of all kind. Using DFT-Cam-B3LYP/ land2dz computations and focused on Hannes Frohlich et al. Halogen Dance (HD) reactions of bromothiophenes, a new bromo-bridged Transition State (TS) is proposed. This bromo-bridged TS was then used to put forth eight possible isomerization as well as eight possible disproportionation paths. These mechanistic pathways were then carefully inspected based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. Collectively these mechanistic pathways joined like a jigsaw puzzle to give, for the first-time, a fully comprehensive cascade-like pattern for base-catalyzed halogen dance in its entirety. The present work may well shed light on a dynamic domino mechanism which dominates the realm of nonaqueous strongly basic medium, organic chemistry, reactions. C-Br reactivity and σ-holes in bromothiophenes are shown to be the major mechanistic driving force in their base catalyzed Halogen dance reactions.

Base-catalyzed halogen dance reaction, has puzzled chemists ever since, to come up with new ideas regarding the mechanism of this beautiful chemical transformation. Series of fast metal-halogen exchanges are among the most recent mechanisms. Using DFT-Cam-B3LYP/ land2dz computations and focused on Halogen Dance (HD) reactions of bromobenzene derivatives, new bromo-bridged Transition States (TS) are proposed. These are then used to lay out 8 possible isomerization and 18 possible disproportionation paths. Mechanistic pathways were then analyzed based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. Overall pattern of these mechanisms draws for the first-time a cascade-like pattern for base-catalyzed halogen dance in its entirety. The present work shed light on a dynamic domino mechanism which dominates the realm of nonaqueous strongly basic medium reactions. Trends like these may well be a shared feature in base digestion of wood for its precious poly aromatic component like lignin.

Medicinal plants have long been known to humans. Special plant species had even attracted animals for their potential drug properties...

Spherical conformational landscape model was revisited to include yet another class of cyclic compounds; the derivatives of cyclohexane. The updated model is not only capable of explaining Raman spectral features in fluxional cyclopentane but is also capable of revealing similarities between cyclopentane and cyclohexane derivatives for the first time. At the heart of the model lies the aspect of B/T ring coordinates (B/T conformational platform) that represents different levels of puckering (q). DFT-ωb97xd/6-311 + G* computations confirmed by MP2/aug cc-pVTZ computations were used to fully investigate 16 different derivatives of both cyclohexane and cyclopentane. Intrinsic reaction coordinate, IRC, computations were performed to gain insight into patterned inter-platform pathways connecting ring coordinates. These pathways revealed the coupling strength between bent/boat, B, and twist, T, ring coordinates. The coupling is found to be stronger for cyclopentane compared to cyclohexane. Some spectral features in the overlap region near 1400 cm−1 show promising signs on spin–spin relaxation, T2, mechanism. The work opens up an avenue for conformational studies of medium-sized rings. Also, ongoing studies to unravel potential relationships between conformational flexibility and bioactivity of cyclic compounds are underway. Conformationally mobile cyclic carbonic skeletons like cis-Octahydropentalenes are occurring in a number of natural products. A complete conformational analysis of cis-Octahydropentalenes reveals how some natural products populate their bioactive form. The pattern successfully explains the bioactive conformation in (+)-epi-goniofufrone and Hirsutic acid, both of which are natural products with potent bioactivity. Analysis like these are illustrative of how nature can use some special scaffolds to achieve maximal bioactivity, which in turn would fuel research in drug design.

Bio chemists have been quite successful in proving that folding patterns in proteins is evolved upon natures ability to populate certain bioactive folded conformers.

The first complete pseudorotational model for conformational analysis of cyclopentane was introduced by Lipnick et al.

Trehalose ability to preserve water in biology has spawned research on this special disaccharide and its solutions. Trehalose unlike any other disaccharide, tend to mix with almost any amount of water. In water, Trehalose forms a hydrodynamic volume with bound waters (both coordination water and semicircular heterogeneities), capable of perturbing the very nature of normal bulk water. Switching of the two major conformational forms, defined by their helicities (i, i-H2O with lower helicity and ii, ii-H2O with higher helicity), were closely examined, using DFT/B3LYP- 6-311 + G** level of theory, along with molecular dynamic (MD) calculations in aqueous media. Patterns in radial distribution functions (RDF) confirmed semicircular heterogeneities, including spines of water (rows of slow water molecules), in Trehalose hydration shell. Dynamics of Trehalose conformational switch and its coordination water are coupled to dynamics of these spines of water, which are themselves coupled to dynamics of the rest of Trehalose hydration shell waters. Like seamless cogwheels such energy cascade links the upstream slow dynamics of spines to the downstream collective bulk water dynamics. This lubricates Trehalose conformational switch through coordination water uptake, for which we proposed a mechanism here. We show how the coupling between Trehalose and bound waters in its hydrodynamic volume encompass both function and dynamic of the molecule and its hydration shell. Further simulations are needed to see how this ability is related to the evading and percolating nature of cryoprotectant water, also reported for the self-coordinating jelly behavior of biological water.

Carbocations, organic chemistry corner stones, play a major role in carbonic skeletal rearrangements. A turning point in their study was the introduction of non-classical Carbocations, which establish a rapid equilibrium among their different forms to distribute their positive charge. Here a new stereospecific mechanistic pathway for cyclopropylcarbinyl and cyclobutyl cations is proposed. Carbon scrambling is plotted into a conformational landscape model, usually used for true conformers. A deeper insight into these cationic interconversions provides the underpinning principals that govern their dynamics. Future studies are expected to reveal the role of cyclopropyl structural motifs in the vast arrays of natural products and their dynamics.

A new, versatile reagent, N,N,N-triphenylselenyl-isocyanuric acid (TPSCA) has been prepared, characterized, and used as a source of the electrophilic phenylselenyl group. This relatively stable compound was utilized for an efficient α-selenenylation reaction of aldehydes and ketones catalyzed by l -prolinamide under mild reaction conditions. The organocatalytic asymmetric α-selenenylation of an aldehyde was also studied and the reaction was found to proceed with high enantioselectivity (96% ee).

In the present work, silica-coated magnetic nanoparticles [Fe3O4@SiO2@C22–Pd(II)] were prepared and characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometer, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, elemental analysis, inductively coupled plasma, thermogravimetric and differential thermal analysis. This heterogeneous catalyst is utilized as an effective catalyst for the Suzuki–Miyaura coupling of arylboronic acids and aryl halides, and the cross-coupling reaction of aryl halides and thiols. The catalyst was easily separated by magnetic decantation and the recovered catalyst was reused for five cycles without any significant loss of the catalytic activity.

A new, versatile reagent, N,N,N-triphenylselenyl-isocyanuric acid (TPSCA) has been prepared, characterized, and used as a source of the electrophilic phenylselenyl group. This relatively stable compound was utilized for an efficient α-selenenylation reaction of aldehydes and ketones catalyzed by l -prolinamide under mild reaction conditions. The organocatalytic asymmetric α-selenenylation of an aldehyde was also studied and the reaction was found to proceed with high enantioselectivity (96% ee).