Stereoselective cascade reactions for construction of polyfunctionalised octahydroquinolines via [2C+2C+1C,1N] cyclisation

A conceptually unifying approach for a highly enantio- and diastereoselective synthesis of polyfunctionalised octrahydroquinolines incorporating three contiguous chiral centres is reported. The synthesis involves diphenylprolinol silyl ether-catalysed Michael addition of 1,3-cyclohexanedione to nitroalkenes followed by potassium carbonate-promoted aza-Henry reaction with N-tosyl aldimines, intramolecular hemiaminalisation and dehydration reaction cascade in a one-pot operation.     

Ionic liquid-promoted one-pot oxidative Michael addition of TMSCN to Baylis-Hillman adducts

The first example of ionic liquid-promoted one-pot oxidative conjugate hydrocyanation of Baylis-Hillman adducts with trimethylsilyl cyanide (TMSCN) is reported. The oxidation of Baylis-Hillman adducts with IBX/[bmim]Br or isomerization-oxidation with NaNO₃/[Hmim]HSO₄ systems affords β-ketomethylene compounds or [E]-cinnamaldehydes, respectively. These α,β-unsaturated carbonyl compounds undergo Michael addition with TMSCN in the same vessel to afford the corresponding thermodynamically more stable β-cyanated products. Thermodynamically less stable 1,2-addition products were not formed. The present regioselective reactions are promoted by ionic liquids, which can be recycled easily for further use without any loss of efficiency.     

Synthetic routes for phenazines: an overview

Phenazines are known to exhibit a diverse range of biological properties, such as antimicrobial, antitumor, antioxidant, antimalarial, neuroprotectant, etc. Owing to their significant applications in both medicinal and industrial fields, the phenazine framework has emerged as a remarkable synthetic target. The most general approaches for synthesis of phenazines include the Wohl–Aue method, Beirut method, condensation of 1,2-diaminobenzenes with 2C-units, reductive cyclization of diphenylamines, oxidative cyclization of 1,2-diaminobenzene/diphenylamines, Pd-catalyzed N-arylation, multicomponent approaches, etc. Advances in the exploitation of synthetic routes for assembly of this scaffold are reported in this review.     

Intra-Specific Chemotypic Variability of Forskolin Content in Coleus forskohlii (Wild.) Briq. Growing in Nilgiri Hills of India

JPC – Journal of Planar Chromatography – Modern TLC - Plant metabolite varies with season and geographic conditions. The present study is aimed at the identification of the potential...     

Synthesis of novel fluorescent benzo[a]pyrano[2,3-c]phenazine and benzo[a]chromeno[2,3-c]phenazine derivatives via facile four-component domino protocol

An efficient and practical route to novel fluorescent benzo[a]pyrano[2,3-c]phenazine framework has been developed by one-pot, four-component reaction of 2-hydroxynaphthalene-1,4-dione, 1,2-phenylenediamines, aromatic aldehydes, and Meldrum’s acid in glacial acetic acid at 70 °C. Photophysical studies of these compounds have been reported. Reactions involving cyclohexane-1,3-dione/5-methylcyclohexane-1,3-dione/dimedone in the place of Meldrum’s acid yielded corresponding benzo[a]chromeno[2,3-c]phenazine derivatives. Crystal structure of 3k established the regioisomer formed. Mild reaction conditions, good yields, short reaction time, and easy separation are some of the salient features of the present protocol.     

Determination of biogenic amines in lake water by micellar electrokinetic chromatography with fluorescence detection after derivatization with fluorescamine

A simple and rapid method has been developed for the determination of biogenic amines in lake water using micellar electrokinetic chromatography with fluorescence detection. Separation of fluorescamine derivatized biogenic amines was accomplished by using borate buffer of pH 9.5 containing 40 mM of sodium dodecyl sulphate. The method has been optimized with respect to fluorescamine concentration, reaction pH, reaction time, separation voltage and injection time. Detection was performed by using UG-11 excitation filter and 495 nm emission filter. The proposed method for histamine, tyramine and dopamine allowed their separation within 2 min with detection limits in nM range. The interday and intraday reproducibility of peak areas were less than 6.5%. Recovery of spiked samples was 95.76–116.31%.     

Enhanced Production of Phenolic Compounds in Compact Callus Aggregate Suspension Cultures of Rhodiola imbricata Edgew.

Applied Biochemistry and Biotechnology - Rhodiola imbricata is a rare medicinal plant of the trans-Himalayan region of Ladakh. It is used for the treatment of numerous health ailments. Compact...     

Strategic applications of Baylis-Hillman adducts to general syntheses of 3-nitroazetidines

A novel one-pot highly diastereoselective synthesis of substituted 3-nitroazetidines via an anionic domino process is described. The synthesis involves a high yielding annulation of Baylis-Hillman alcohols and their aldehydes with either N-aryl/tosylphosphoramidates or N-aryl/tosylphosphoramidates in combination with a task-specific ionic liquid [bmim][X-Y] to afford the corresponding 1,2,3-tri- and 1,2,3,4-tetrasubstituted azetidines, respectively. Plausible mechanisms for the formation of various 3-nitroazetidines have been suggested.