KI‐VO(acac)2‐H2O2‐AcOH,A New Iodinating System for Selective Iodination at C‐5 Position of Activated Pyrimidinediones: A Combined Experimental and Density Functional Study

KI‐VO(acac)₂‐H₂O₂ in aqueous ethanolic medium with acetic acid as additive has been found to iodinate pyrimidinediones and aromatic amines. The methodology is mild, efficient, and environmentally benign. Density functional theory‐based reactivity parameters support the experimentally observed reactivity of pyrimidinedione derivatives.     

Some new modular equations in Ramanujan’s alternate theory of signature 3

The Ramanujan Journal - In this paper, we prove some new modular equations in the theory of signature 3 or cubic modular equations by using theta-function identities. Particularly, we prove modular...     

An improved stereoselective total synthesis of (R)-rugulactone

A novel route for the stereoselective total synthesis of (R)-rugulactone 1 has been developed, starting from substituted epoxide 4 and 3-phenylpropionaldehyde 5 employing Julia-Kocienski olefination as a key step to construct E-configured α,β-unsaturated keto-group. The overall yield of the synthesized rugulactone is 19.94% and is better than the reported methods.     

Synthesis of oxabicyclo[3.3.1]nonenes and substituted tetrahydropyrans via (3,5)-oxonium-ene reaction

An efficient methodology for the synthesis of oxabicyclo[3.3.1]nonenes and substituted tetrahydropyrans has been developed in moderate yields from the reaction of geraniol with aldehydes and epoxides promoted by boron trifluoride etherate.     

Identification of Potential Vaccine Candidates Against Streptococcus pneumoniae by Reverse Vaccinology Approach

In the past few decades, genome-based approaches have contributed significantly to vaccine development. Our aim was to identify the most conserved and immunogenic antigens of Streptococcus pneumoniae, which can be potential vaccine candidates in the future. BLASTn was done to identify the most conserved antigens. PSORTb 3.0.2 was run to predict the subcellular localization of the proteins. B cell epitope prediction was done for the immunogenicity testing. Finally, BLASTp was done for verifying the extent of similarity to human proteome to exclude the possibility of autoimmunity. Proteins failing to comply with the set parameters were filtered at each step. Based on the above criteria, out of the initial 22 pneumococcal proteins selected for screening, pavB and pullulanase were the most promising candidate proteins.     

A convenient synthesis of novel 5-aryl-pyrido[2,3-d]pyrimidines and screening of their preliminary antibacterial properties

Exploiting the diene nature of 6-[1-aza-2-(dimethylamino)prop-l-enyl]-1,3-dimethyluracil (2), novel 5-aryl-pyrido[2,3-d]pyrimidines (5a–h) have been synthesized. The reaction proceeds through a triene intermediate whose structure has been conclusively established by single crystal X-ray analysis. Role of water is intriguing as the reaction can be stopped at the intermediate stage. Synthesized compounds have been screened for possible antibacterial properties and results showed modest activity.     

Base-promoted three-component cascade approach to unsymmetrical bis(indolyl)methanes

Here we report a base-catalyzed reaction of two different indoles with aldehydes under heating to produce unsymmetrical bis(indolyl)methanes (BIMs), in which one of the indole ring must be N-substituted. Mixture of EtOH-H₂O is used as solvent. The reaction did not give symmetrical BIMs of N-substituted indoles or N–H indoles. However, traces of latter were formed in few cases, especially when electron-rich aldehydes were used. Diversely substituted indoles and aldehydes were used for the reaction. The reaction proceeds via 3-indolylalcohol, which we confirmed through isolation. The method also gives good yield on multigram scale reaction.     

Palladium(0)-catalyzed addition of CFBr3 to olefins: synthesis of 1,1,3-tribromo-1-fluoroalkanes and 1,2-difluoroalkenes

It has been observed that Pd(0) can be used as a catalyst for the addition of CFBr₃ to olefins to give 1,1,3-tribromo-1-fluoroalkanes with good yields. Both terminal and internal olefins react under these conditions. Treatment of the addition product with zinc and methanol gave 1,2-fluoroalkenes.     

Methanol aided synthesis of PdNPs decorated on montmorillonite K 10 and its implication in Suzuki Miyaura type cross coupling reaction under base free condition

An efficient catalyst PdNPs decorated on Montmorillonite K 10 is prepared by simply stirring Pd(OAc)₂ in methanol at room temperature without using any external reducing agent. The catalyst shows excellent activity for Suzuki Miyaura type cross coupling reaction between aryl diazonium salt and arylboronic acid under ligand and base free reaction conditions within short reaction time. The main advantage of this methodology is the easy synthesis of heterogeneous PdNPs @ Mont K 10 catalyst in a mild condition without using any reducing agent or additive and the catalyst is very efficient for biaryl synthesis. The catalyst is well characterized by SEM, EDX, TEM, BET, Powder XRD, TGA, DSC etc. The reaction pathway is greener with aqueous reaction medium, base free reaction condition, room temperature and reusable heterogeneous catalyst.     

Ferrocene conjugated copper(II) complexes of terpyridine and traditional Chinese medicine (TCM) anticancer ligands showing selective toxicity towards cancer cells

Six novel mixed‐ligand copper(II) complexes, namely, [Cu(R‐tpy)(L)]NO₃ ( 1–6 ), where R‐tpy is 4′‐phenyl‐2,2′:6′,2′′‐terpyridine (Ph‐tpy; 1–3 ) and 4′‐ferrocenyl‐2,2′:6′,2′′‐terpyridine (Fc‐tpy; 4–6 ), L is the bidentate O,O donor monoanion of plumbagin (5‐hydroxy‐2‐methyl‐1,4‐naphthoquinone; plum in 1 , 4 ), chrysin (5,7‐dihydroxyflavone; chry in 2 , 5 ) and curcumin (bis(4‐hydroxy‐3‐methoxyphenyl)‐1,6‐diene‐3,5‐dione; curc in 3 , 6 ) have been synthesized and characterized and their in vitro cytotoxicity against cancer cells is evaluated. The energy optimized structures and the frontier orbitals of the complexes have been obtained from the DFT calculations. Complexes 4–6 with a conjugated ferrocenyl moiety and TCM anticancer ligands, namely, plum (in 4 ), chry (in 5 ) and curc (in 6 ) showed potent cytotoxicity giving respective IC₅₀ values of 1.2 μM, 0.62 μM and 0.21 μM in HeLa and 2.0 μM and 1.0 μM and 0.34 μM in MCF‐7 cancer cells while being much less toxic to MCF‐10A normal cells (IC₅₀: 8.3‐17.1 μM). In contrast, complexes 1–3 with a conjugated phenyl moiety were appreciably less toxic to HeLa cells with respective IC₅₀ values of 10.4 μM, 8.1 μM and 5.5 μM when compared with their ferrocenyl analogues 4–6 . Mechanistic studies using Hoechst staining and Annexin‐V‐FITC assays on cancer cells revealed an apoptotic pathway of cell death induced by the complexes. Fluorescence imaging study showed that complex 6 having curcumin as ligand localized primarily in the mitochondria of HeLa cells. Thus, we demonstrate in this study that ferrocene conjugation to copper(II) complexes of TCM anticancer ligands significantly increases the selectivity and cytotoxicity of the resulting complexes towards cancer cells over normal cells.