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Synthesis of polyhydroquinolines via Hantzsch’s multicomponent reaction (MCR) involves the use of a hygroscopic and moderately toxic ammonium salt as one of the key reactants. In our effort, we have found urea as an effective ammonia surrogate when the MCR was performed in the presence of sulphonic acid-functionalized Wang resin (Wang-OSO3H) as a polymeric and recoverable acidic catalyst under green conditions. Urea is relatively less hygroscopic/toxic than the commonly used ammonium salts used in this MCR. The methodology afforded a range of polyhydroquinolines in good yields. Depending on the nature of reaction conditions employed, the MCR afforded Biginelli product or 1,4-DHPs when the use of 1,3-diketone was omitted.

We report here an easy, efficient and green synthetic protocol for the (E)-1-aryl-3-(2-morpholinoquinolin-3-yl)prop-2-en-1-ones by the Claisen-Schmidt condensation of 2-morpholinoquinoline-3-carbaldehyde and different substituted acetophenones by using 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim)BF4. The compounds were characterized by using 1H NMR, 13C NMR and mass spectral data and screened there in vitro antimicrobial activity against different bacterial and fungal organisms.

A highly efficient synthesis of (S)-1-(furan-2-yl)pent-4-en-1-ol, known to be an initial precursor of Ipomoeassin family of compounds and C1–C15 domain of halichondrins has been achieved via a sequence involving the use of Weinreb amide formation followed by Weinreb ketone synthesis and finally CBS (Corey–Bakshi–Shibata) reduction. Detailed study on improvement of each step is described. The title compound was converted to a potential cytotoxic agent for further pharmacological studies.

Objectives Leflunomide (LFNM) is a drug that belongs to isoxazole derivatives and has immunosuppressive and anti-inflammatory activities. A literature search confirms that there is no method reported for the simultaneous estimation of LFNM and its related impurities A and B in pharmaceutical dosage forms or in bulk drug. Hence the present work aimed to develop a simple stability indicating RP-HPLC method for the separation and quantification of LFNM and its impurities A and B. Materials and methods Systematic trials of method conditions like mobile phase ratio, pH, flow rate, stationary phase, and detector wavelength were performed for the simultaneous analysis of LFNM and its related impurities A and B. The developed method was validated as per the ICH guidelines including forced degradation studies in different stress conditions. Results Optimized separation was achieved on a Thermo Scientific Hypersil ODS C18 column (250 mm×4.6 mm; 5 μm id) using mobile phase composition of acetonitrile, methanol, and 0.1 M sodium perchlorate in the ratio of 40:30:30 (v/v), pH 4.6, at a flow rate of 1.0 mL/min in isocratic elution. UV detection was carried out at a wavelength of 246 nm. Well-resolved peaks were observed with high numbers of theoretical plates, lower tailing factor, and reproducible relative retention time and response factor. The method was validated and all the validation parameters were found to be within the acceptance limits. Stability tests were done through exposure of the analyte solution to five different stress conditions, i.e. 1 N HCl, 1 N NaOH, 3% H2O2, thermal degradation of powder, and exposure to UV radiation. The method can successfully separate the degradation products along with both the impurities studied. The % degradation was also found to be less. Conclusion The method developed for LFNM is simple and precise and can be applied for the separation and quantification of LFNM and its related impurities in bulk drug and pharmaceutical formulations.

The chelating ligands 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) and 3,6-bis(3-pyridyl- 1-pyrazolyl)pyridazine (bppp), were prepared by the condensation of pyridylpyrazole and 3,6-dichloropyridazine. The mononuclear complexes [(η 6-arene)Ru(pp-Cl)Cl] + {η 6-arene = C6H6 (1); p-iPrC6H4Me (2)}, [(η 5-C5Me5)M(pp-Cl)] + {M = Rh (3); Ir (4)}, [(η 6-arene)Ru(bppp)Cl] + {η 6-arene = C6H6 (5); p-iPrC6H4Me (6)}, [(η 5-C5Me5)M(bppp)] + {M =Rh (7); Ir (8)} as well as the binuclear complexes [{(η 6-arene)RuCl}2(bppp)]2 + {η 6 -arene =C6H6 (9); p-iPrC6H4Me (10)} and [{(η 5-C5Me5)MCl}2(bppp)]2 + {M = Rh (11); Ir (12)} have been synthesized from 3-chloro-6-(3-pyridyl-1-pyrazolyl)pyridazine (pp-Cl) or 3,6-bis(3-pyridyl-1-pyrazolyl)pyridazine (bppp) and the corresponding dimers [(η 6-arene)Ru(μ-Cl)Cl]2 and [Cp*M(μ-Cl)Cl]2, respectively. All complexes were isolated as their hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV-visible spectroscopy. The molecular structures of [2]PF6 and [7]PF6 have been established by single crystal X-ray structure analysis.

A family of novel platinum group metal complexes containing bidentate chelating 1-pyrimidyl-3-methylimidazolyl bromide ( HL1 · Br ) and 1-pyrimidyl-3-methylimidazolyl-2-thione ( L2 ) ligands has been synthesized. The synthetic protocol for the formation of these complexes differs from one ligand to the other. Treatment of ligand ( HL1 · Br ) with the metal precursors led to the formation of complexes via in situ carbene transfer reactions. The silver–NHC complex ( 1 ) was formed by the reaction of HL1 · Br with silver oxide under light-free conditions. Subsequent addition of appropriate metal precursors to the silver–NHC complex yielded [(η 6 -arene)Ru( L1 )Cl]PF 6 complexes {arene = C 6 H 6 ( 2 ), p - i PrC 6 H 4 Me ( 3 ), C 6 Me 6 ( 4 )} on stirring at room temperature, whereas the complexes [CpRu( L1 )(PPh 3 )]PF 6 {Cp = C 5 H 5 (5), C 9 H 7 ( 6 )} were obtained under reflux conditions. In the case of ligand L2 , stirring of equimolar quantities of metal precursors and the ligand at room temperature yielded [(η 6 -arene)Ru( L2 )Cl]PF 6 {arene = C 6 H 6 (7), p - i PrC 6 H 4 Me ( 8 ), C 6 Me 6 ( 9 )}, and [Cp ∗ M( L2 )Cl]PF 6 {Cp ∗ = C 5 Me 5 , M = Rh ( 10 ), Ir ( 11 )}. All these complexes were characterized by CHN analysis, IR, NMR and mass spectrometry besides confirmation by single crystal X-ray diffraction studies for some representative complexes as their hexafluorophosphate salts [ 3 ]PF 6 , [ 5 ]PF 6 , [ 8 ]PF 6 and [ 10 ]PF 6 .

Reaction of two equivalents 4-{(3-(pyridine-2-yl) 1H-pyrazole-1-yl}methyl benzonitrile (L1) and 3-{(3-(pyridine-2-yl)1H-pyrazole-1-yl}methyl benzonitrile (L2) with one equivalent of [(η6-arene)Ru(μ-Cl)Cl]2 and [Cp*M(μ-Cl)Cl]2 in methanol yielded mononuclear complexes of the formulae [(η6-arene)Ru(L1/L2)Cl]BF4{arene =C6H6 (1, 6); C10H14 (2, 7); C6Me6 (3, 8)} and [Cp*M(L1/L2)Cl]PF6/BF4 {Cp*= η5-C5Me5, M=Rh (4, 8); Ir (5, 10)}. These complexes are characterized by IR, 1H NMR and identities of the structure are established by single crystal XRD studies of some of the representative complexes. It is confirmed from the spectral studies that the nitrile group is not taking part in complexation; instead it remains as a free pendant group only.

A family of platinum group metal complexes containing bidentate pyridazine–NHC ligands (L1 = 3,6-bis(N-n-methylimidazolyl)pyridazine dichloride, L2 = 3,6-bis(N-n-butylimidazolyl)pyridazine dichloride) have been synthesized. The typical mechanism of the reactions for these syntheses involved an in situ carbene transfer reactions. Reaction of L1/L2 with silver oxide in absence of light yielded silver–NHC complexes (1) and (2). When, the respective metal precursors were added to the silver–NHC complexes, transmetallation occurred with the possible isolation of the following cationic complexes: [(η6-C6H6)Ru(L)Cl]2+ {L = L1 (3), L2 (5)}, [(η6-p-iPrC6H4Me)Ru(L)Cl]2+ {L = L1 (4), L2 (6)}, [Cp∗Rh(L)Cl]2+ {L = L1 (7), L2 (9)} and [Cp∗Ir(L)Cl]2+ {L = L1 (8), L2 (10)}. All these complexes were stable in ambient atmosphere, and could be obtained in good yield. All these complexes were characterized by spectroscopic analyses. The molecular structure of the complex 9 was determined by single crystal X-ray diffraction studies.

A new Schiff base, (pyridin-2-yl)-N-(3,5-di(pyridin-2-yl)-4H-1,2,4-triazol-4-yl)methanimine, (L), was synthesized. Reaction of [(η6-arene)Ru(µ-Cl)Cl]2 and [Cp*M(µ-Cl)Cl]2 (M = Rh and Ir) with one equivalent of L in the presence of NH4PF6 in methanol yielded dinuclear complexes, [(η6-arene)2Ru2(L-OH)Cl](PF6)2 {arene = C6H6 (1), p-iPrC6H4Me (p-cymene) (2) and C6Me6 (3)}, and [Cp*2M2(L-OH)Cl](PF6)2 [M = Rh (4) and Ir (5)], respectively, leading to the formation of five new chiral complexes with –OH on the azomethine carbon. L is a pentadentate ligand where one of the metal centers is coordinated to two nitrogen atoms in a bidentate chelating fashion while the other metal is bonded tridentate to three nitrogen atoms. Although the ligand is neutral before coordination, after complexation it is anionic (uni-negative) with negative charge on the azo nitrogen {see the structures: N(5) in 2[PF6]2 and N(3) for 4[PF6]2}. The complexes have been characterized by various spectroscopic methods including infrared and 1H...

A dehydrative annulation strategy involving an intramolecular ring closure under a Mitsunobu type reaction condition has been used for the construction of octahydroindolizine framework successfully. This strategy that was reported to be unsuccessful when applied to a similar other system allowed us to perform a diastereoselective synthesis of (6R, 8aS)-octahydroindolizin-6-ol [a precursor of (-)-8a-epidesacetoxyslaframine] starting from commercially available chiral (S)-epichlorohydrin via a piperidine intermediate i.e., (3R, 6S)-6-(3-hydroxypropyl)piperidin-3-ol. The methodology has potential to afford a library of optically pure small molecules of pharmacological importance based on the related indolizine framework.