Syntheses of the Macrocyclic Spermine Alkaloids (±)‐Budmunchiamine A – C

The syntheses of four macrocyclic spermine alkaloids, (±)‐budmunchiamine A – C ( 1a – c ) and (±)‐budmunchiamine L4 ( 1 ), were accomplished by Michael addition of spermine to the α,β‐unsaturated esters 3a – d , followed by cyclization of the resulting α,ω‐tetraamino esters 4a – d with triethoxyantimony; N‐methylation of the amino lactams 6a – c yielded the budmunchiamines A – C ( 1a – c ).     

Ein neuer Reaktionsweg zu 1, 3-Dicarbonylderivaten. Modelluntersuchungen am A/B-Teil von 3-Oxo-5α-steroiden

A New Route to 1, 3-Dicarbonyl Derivatives, Model Investigations on the A/B-Part of-3-Oxo-5α-steroids Starting from 1 the 1, 3-dicarbonyl compounds 4a – d were synthetized via the enynes 2a – e and the relatively unstable epoxides 3a – d . The latter were reacted with 95% formic acid to gave 4a – d ; small amounts of the furane derivatives 5a – c were identified as by-products in this last step. In the presence of catalytic amounts of HgSO₄ the epoxides 3a – c yielded with 95% formic acid the furanes 5a – c , but no detectable amounts of 4a – c .     

Development and validation of thin-layer chromatography and high-performance thin-layer chromatography methods for the simultaneous determination of linagliptin and empagliflozin in their co-formulated dosage form

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, simple and validated thin-layer chromatography (TLC) method (method A) and a high-performance thin-layer...     

Synthesis and Reactions of Pyrido[2,1‐a]isoquinolin‐4‐yl Formimidate Derivatives and Antimicrobial Activities of Isolated Products

Treatment of arylidene malononitriles 2A – C with 1‐cyanomethylisoquinoline 1 afforded 4‐amino‐2‐arylpyrido[2,1‐a ]isoquinoline‐1,3‐dicarbonitrile derivatives 5A – C , which converted to formimidates 6A – C via reaction with triethylorthoformate. Treatment of the latter compounds with hydrazine hydrate gave the corresponding amino–imino compounds 7A – C , which underwent Dimroth rearrangement to afford 13‐aryl‐1‐hydrazinylpyrimido[5′,4′:5,6]pyrido[2,1‐a ]isoquinoline‐12‐carbonitrile 8A – C . The latter reacted with aldehyde to give 9a – i . Oxidative cyclization of the latter compounds 9a – i gave [1,2,4]triazolo[4″,3″:1′,6′]‐pyrimido[5′,4′:5,6]pyrido[2,1‐a ]isoquinolines 10a , d , g . Such compounds isomerized to the thermodynamically more stable isomers [1,2,4]triazolo[1″,5″:1′,6′]pyrimido[5′,4′:5,6]‐pyrido[2,1‐a ]isoquinolines 11a , d , g . Antimicrobial activities for some compounds were studied.     

Application of Densitometry for Determination of Beta-Adrenergic-Blocking Agents in Pharmaceutical Preparations

JPC – Journal of Planar Chromatography – Modern TLC - A chromatographic-densitometric method has been established for identification and quantitation of selected...     

Densitometric HPTLC Method for Simultaneous Quantification of Sennosides A and B and Gallic Acid in a Pharmaceutical Dosage Form

JPC – Journal of Planar Chromatography – Modern TLC - A densitometric HPTLC method has been established for simultaneous quantification of sennosides A and B and gallic acid in a...     

Optimization of the TLC Separation of Seven Amino Acids

JPC – Journal of Planar Chromatography – Modern TLC - A ternary mobile phase for thin-layer chromatographic separation and identification of seven amino acids on microcrystalline...     

Densitometric Determination of Naproxen,and of Naproxen Methyl Ester,its Impurity,in Pharmaceutical Preparations

JPC – Journal of Planar Chromatography – Modern TLC - A chromatographic–densitometric method has been established for identification and quantification of...     

Efficient Synthesis of α‐Benzylidene‐γ‐methyl‐γ‐butyrolactones

A concise synthesis of α‐benzylidene‐γ‐methyl‐γ‐butyrolactones 5a – g from substituted benzaldehydes is described. Compounds 1a – g on reaction with phosphorane 2 , provide the pentenoates 3a – g , which can be hydrolyzed to the acids 4a – g . The latter are cyclized to the corresponding butyrolactones 5a – g in excellent yields. The pentenoates 3a – g , on acid catalyzed cyclization, also provide 5a – g in very high yields.     

Inherent stability testing of empagliflozin in the presence of metformin HCl by HPTLC and characterization of degradation products of empagliflozin by LC–ESI–QTOF–MS/MS

JPC – Journal of Planar Chromatography – Modern TLC - A successful attempt has been made to develop and validate a stability-indicating high-performance thin-layer chromatography...     

Influence of Spiral Framework on Nonlinear Optical Materials

A series of spiral donor–π–acceptor frameworks (i.e. 2 – 2 , 3 – 3 , 4 – 4 , and 5 – 5 ) based on 4‐nitrophenyldiphenylamine with π‐conjugated linear acenes (naphthalenes, anthracenes, tetracenes, and pentacenes) serving as the electron donor and nitro (NO₂) groups serving as the electron acceptor were designed to investigate the relationships between the nonlinear optical (NLO) responses and the spirality in the frameworks. A parameter denoted as D was defined to describe the extent of the spiral framework. The D value reached its maximum if the number of NO₂ groups was equal to the number of fused benzene rings contained in the linear acene. A longer 4‐nitrophenyldiphenylamine chain led to a larger D value and, further, to a larger first hyperpolarizability. Different from traditional NLO materials with charge transfer occurring in the one‐dimensional direction, charge transfer in 2 – 2 , 3 – 3 , 4 – 4 , and 5 – 5 occur in three‐dimensional directions due to the attractive spiral frameworks, and this is of great importance in the design of NLO materials. The origin of such an enhancement in the NLO properties of these spiral frameworks was explained with the aid of molecular orbital analysis.     

Evaluation of the Lipophilicity of Some 1-Arylpiperazines by Planar Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - The lipophilic character of some biologically active 1-arylpiperazines has been studied. A reversed-phase planar chromatographic...     

RPTLC Determination of log P of Structurally Diverse Neutral Compounds

JPC – Journal of Planar Chromatography – Modern TLC - A validated reversed-phase thin-layer chromatographic (RPTLC) method is proposed for parallel estimation of the lipophilicity of...     

Validation of a High-Performance Thin-Layer Chromatographic Method,with Densitometric Detection,for Quantitative Analysis of Nebivolol Hydrochloride in Tablet Formulations

JPC – Journal of Planar Chromatography – Modern TLC - A quantitative densitometric high-performance thin-layer chromatographic method for determination of nebivolol hydrochloride in...     

Thin-Layer Chromatographic Determination of Alpha-Amyrin in the Bark of Mallotus philippensis Lamk

JPC – Journal of Planar Chromatography – Modern TLC - A simple, precise, and accurate high-performance thin-layer chro-matographic method has been established for determination of...     

Development and Validation of an HPTLC Method for the Analysis of Oleanolic Acid from the Roots of Helicteres isora Linn.

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive and reliable high-performance thin-layer chromatographic (HPTLC) method has been developed for the quantitative...     

Development and Validation of HPTLC Method for Simultaneous Determination of Quercetin and Kaempferol in Leaves of Two Chemotypes of Centella asiatica

JPC – Journal of Planar Chromatography – Modern TLC - A simple, accurate and precise high-performance thin-layer chromatography (HPTLC) method was developed and validated for the...     

Application of Multiple-Gradient Thin-Layer Chromatography for the Quantitative Determination of Convallatoxine in Herba Convallariae

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatographic method with densitometric detection has been used to determine the convallatoxine...     

TLC-Densitometric Determination of Azithromycin in Pharmaceutical Preparations

JPC – Journal of Planar Chromatography – Modern TLC - A thin-layer chromatographic method with densitometric detection has been established for quantification of azithromycin in...     

TLC Detection of Chemical Interactions of Vitamins A and D with Drugs

JPC – Journal of Planar Chromatography – Modern TLC - Thin-layer chromatography has been used to investigate possible chemical interactions of vitamins A and D with frequently used...