A facile synthesis of melatonergic antidepressant agomelatine

Agomelatine was synthesized from 8-aminonaphthalen-2-ol by diazotization-iodination, formylation, C–C bond formation by nitroaldol and Pd/C hydrogenation of β-nitrovinylnaphthalene followed by N-acetylation. The route reported employs readily and commercially viable starting materials and reagents, and can potentially be utilized for process synthesis of agomelatine.     

A novel tandem ene/Prins cyclization for the synthesis of octahydropyrano[2,3-c]pyrrole derivatives

A tandem ene/Prins cyclization of olefin tethered aldehyde with an aldehyde has been accomplished using 5 mol % scandium triflate at ambient temperature to afford a novel series of cis-fused octahydropyrano[2,3-c]pyrrole derivatives in good yields with high selectivity. This is the first report on a tandem cyclization of 4-methyl-N-(3-methylbut-2-enyl)-N-(2-oxoethyl)benzenesulfonamide with aldehydes.     

Design and analysis of low power high-speed 1-bit full adder cells for VLSI applications

This paper presents a low power and high speed two hybrid 1-bit full adder cells employing both pass transistor and transmission gate logics. These designs aim to minimise power dissipation and reduce transistor count while at the same time reducing the propagation delay. The proposed full adder circuits utilise 16 and 14 transistors to achieve a compact circuit design. For 1.2 V supply voltage at 0.18-μm CMOS technology, the power consumption is 4.266 μW was found to be extremely low with lower propagation delay 214.65 ps and power-delay product (PDP) of 0.9156 fJ by the deliberate use of CMOS inverters and strong transmission gates. The results of the simulation illustrate the superiority of the newly designed 1-bit adder circuits against the reported conservative adder structures in terms of power, delay, power delay product (PDP) and a transistor count. The implementation of 8-bit ripple carry adder in view of proposed full adders are finally verified and was observed to be working efficiently with only 1.411 ns delay. The performance of the proposed circuits was examined using Mentor Graphics Schematic Composer at 1.2 V single ended supply voltage and the model parameters of a TSMC 0.18-μm CMOS.     

Facile Chemoenzymatic Synthesis of O‐Mannosyl Glycans

O Mannosylation is a vital protein modification involved in brain and muscle development whereas the biological relevance of O‐mannosyl glycans has remained largely unknown owing to the lack of structurally defined glycoforms. An efficient scaffold synthesis/enzymatic extension (SSEE) strategy was developed to prepare such structures by combining gram‐scale convergent chemical syntheses of three scaffolds and strictly controlled sequential enzymatic extension catalyzed by glycosyltransferases. In total, 45 O‐mannosyl glycans were obtained, covering the majority of identified mammalian structures. Subsequent glycan microarray analysis revealed fine specificities of glycan‐binding proteins and specific antisera.     

Synthesis and Spectral Characterization of Related Substances of Lacidipine,an Antihypertensive Drug

Five related substances (impurities) were detected in lacidipine bulk drug substance by a simple high-performance liquid chromatographic method (HPLC) and were identified by liquid chromatography–mass spectrometry (LC-MS). These related substances were independently synthesized, characterized, and co-injected with the sample containing impurities.     

On the fluctuations of independent copies of moving maxima

Let {X_n, n1} be a sequence of independent random variables (r.v.'s) with a common distribution function (d.f.) F. Define the moving maxima Y_k(n)=max(X_n−k(n)+1,X_n−k(n)+2,…,X_n), where {k(n), n1} is a sequence of positive integers. Let Y_k(n)¹ and Y_k(n)² be two independent copies of Y_k(n). Under certain conditions on F and k(n), the set of almost sure limit points of the vector consisting of properly normalised Y_k(n)¹ and Y_k(n)² is obtained.     

Clay Catalysed Convenient Isomerization of Natural Furofuran Lignans Under Microwave Irradiation

The naturally occuring furofuron lignans, (+)-sesamin, (+)-eudesmin, (+)-syringaresinol and (+)-yangambin underwent rapid isomerization to their corresponding C-7 epimers under microwave irradiation in the presence of montmorillonite KSF as catalyst.     

Development and validation of a reversed-phase HPLC method for determination of nitrendipine in rat plasma: application to pharmacokinetic studies

A simple and sensitive method for the determination of nitrendipine in rat plasma was developed using high-performance liquid chromatography (HPLC). The procedure involves extraction of nitrendipine in dichloromethane/sodium hydroxide, followed by reversed phase HPLC using a Waters, Spherisorb ODS2 (250 x 4.6 mm, 5 microm) column and UV detection at 238 nm. The retention times of nitrendipine and internal standard (felodipine) were 5.0 min and 7.5 min, respectively. The calibration curves were linear over the range of 5 ng/mL (lower limit of quantification, LOQ) to 200 ng/mL for nitrendipine. The intra- and inter-day coefficients of variation for all criteria of validation were less than 15% over the linearity range. The sensitivity and precision of the method were within the accepted limits (< 15%) throughout the validation period. The present method was also successfully applied for the study of plasma pharmacokinetics of nitrendipine loaded solid lipid nanoparticles (SLN) in rats.     

The influence of electronic factors on Pd-mediated cycloisomerization: a systematic investigation of competitive 6-exo-dig versus 7-endo-dig cyclizations of sugar alkynols

Pd-mediated cycloisomerization of 3-C-propargyl-ribo- and allofuranose derivatives was investigated in detail to understand the influence of electronic factors on the regioselectivity (6-exo- vs 7-endo) of alkynol cycloisomerization leading either to a six- or seven-membered ring. In general, the 6-exo-dig mode of cyclization is facile and is independent of electronic factors. With some of the alkynols, a regioselective (7-endo?) hydration of the alkyne unit was observed and this has been attributed to the participation of C(3)-OH. When the C(3)-OH was protected as its benzyl ether, cycloisomerization of these alkynols occurred exclusively in a 6-exo-dig mode resulting in the corresponding [3.2.1]-bicyclic ketals. Additional control experiments conducted were in support of the participation of C(3)-OH in regioselective alkyne hydration.     

Effects of acyl donor type, catalyst type, and reaction conditions on the activity and selectivity of Friedel-Crafts acylation

Acylation of anisole and 3-methylanisole was performed with several acylating reagents (acetylation by AcCl and Ac₂O and bromoacetylation by BrAcCl and (BrAc)₂O) over different solid acid catalysts. The reaction conditions were optimized with respect to the acylation reagent, overall yield, solid acid catalyst, and the products selectivities. While acylation of anisole with acetyl chloride or acetic anhydride resulted in its full conversion to para-substituted acetophenone, the use of bromoacetyl bromide or bromoacetic anhydride yielded also the ortho-substituted product. Acylation of 3-methylanisole also yielded both para- and ortho-substitutions, and the products distribution was affected by the reaction conditions and catalyst type. It was found that while more acidic catalysts (caesium salt of heteropolyacid and zeolites) were the most active towards anisole acylation, the most active catalysts for the acylation of 3-methylanisole were ion-exchange catalysts. Employing HY-740 zeolite resulted in the highest ortho-selectivity in the acylation of anisole with bromoacetyl bromide and bromoacetic anhydride and in the acylation of 3-methylanisole with acetic anhydride.