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Catalytic Bu4NOAc as silicon activator of ethyl 2-(trimethylsilyl) acetate, in THF, was utilized for the synthesis of β-hydroxy esters, whereas employing catalytic Bu4NOTMS gave α,β-unsaturated esters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated β-hydroxy esters with subsequent elimination to form the α,β-unsaturated ester has been demonstrated. The key to selective product formation lies in use of the weaker acetate activator which suppresses subsequent elimination whereas stronger TMSO– activator (and base) facilitates both addition and elimination steps. The use of tetrabutyl ammonium salts for both acetate and trimethylsilyloxide activators provide enhanced silicon activation when compared to their inorganic cation counterparts. [ABSTRACT FROM AUTHOR]

The synthesis of the reagent 2,2-bis(trimethylsilyl)-1,3-dithiane was directly achieved in an excellent yield from 1,3-dithiane in one step. The bench-stable reagent can be utilized for Peterson olefinations using either TMSOK/Bu4NCl or fluoride ion as promoter of α-silyl carbanion formation, thereby generating ketene dithioacetals, which are versatile intermediates in organic synthesis. Olefination reactions were successfully achieved with aromatic, heteroaromatic, aliphatic aldehydes and ketones. [ABSTRACT FROM AUTHOR]

Highly regioselective benzylic metalations in hydrocarbon solvent have been achieved at rt and 0 °C using a mixed-metal Li/K-TMP amide comprised of KOtBu, BuLi, and 2,2,6,6,-tetramethylpiperidine (TMP(H)). Mixing of KOtBu, BuLi, and TMP(H) in heptane gave a solution of the base mixture which when used in deuterium labeling experiments confirmed the requirement of the three reagent components for both reactivity and selectivity. The reaction protocol is operationally straightforward and found to be applicable to a broad range of substrates. Upon generation of the metalated products, they are reacted in heptane at ambient temperature in a variety of synthetically useful ways. Illustrated examples include generation of the benzyltrimethylsilanes and α,α-bis(trimethylsilyl)toluenes reagents, which are bench-stable surrogates of benzyl anions and α-silyl carbanions utilized for nucleophilic addition and Peterson olefination reactions. Direct C-C couplings mediated by 1,2-dibromoethane provided entries into bibenzyls and [2.2]metacyclophanes. Comparison of reaction outcomes with the same reactions carried out in THF at -78 °C showed no negative effects for conducting the reactions under these milder more user-friendly conditions. [ABSTRACT FROM AUTHOR]

The synthesis of bench-stable α,α-bis(trimethylsilyl)toluenes and tris(trimethylsilyl)methane is described and their use in stereoselective Peterson olefinations has been achieved with a wide substrate scope. Product stereoselectivity was poor with carbonyl electrophiles ( E/ Z ∼1:1 to 4:1) though this was significantly improved by employing the corresponding substituted N-benzylideneaniline (up to 99:1) as an alternative electrophile. The olefination byproduct was identified as N, N-bis(trimethylsilyl)aniline and could be easily separated from product by aqueous acid extraction. Evidence for an autocatalytic cycle has been obtained. [ABSTRACT FROM AUTHOR]

Abstract: In continuation with our previous work in anti-TB research area, in the present study we have demonstrated the structural diversity of quinolylhydrazides as potent anti-tuberculars. The compound library was synthesized by molecular hybridization approach and tested in vitro against Mycobacterium tuberculosis H37Rv strains. Among the designed conjugates, the most promising molecules were found to exhibit 100% Growth Inhibition (GI) at MIC <6.25μg/mL. Moreover, several analogs in the designed series were also turned out as excellent anti-tuberculars. To probe the structural characteristics influencing on the SAR, the classification model was generated using a binary QSAR approach termed recursive partitioning (RP) analysis. The significant features outlined by the RP model act as a guide in order to design the ‘lead’ compound. [Copyright &y& Elsevier]

Abstract: An efficient protocol for the syntheses of diverse 2,6,7- and 2,6,9-trisubstituted purines is reported starting from the guanine precursor, 2-amino-6-chloropurine nucleoside through subsequent regioselective, high yielding Mitsunobu coupling and nucleophilic substitutions at C6 with versatile primary and secondary amines. A wide range of 2,6,7- and 2,6,9-trisubstituted purines were accessible in good to excellent yields with remarkable functional group tolerance. Moreover, solvent-free, large scale synthesis of precursors 2 &3 and facile preparation of organophosphorus side chains 4 &5 were also accomplished with excellent yields. [Copyright &y& Elsevier]

Tuberculosis caused by Mycobacterium tuberculosis remains a leading cause of mortality worldwide into 21st century. In continuation with our anti-tuberculosis research programme, in this work, we have prepared molecularly diverse coumarins clubbed with benzothiazepines as well as its aza-analogues-benzodiazepines by molecular hybridization. The resulting compounds were screened for their M. tuberculosis activity against H37Rv strains using microplate alamar blue assay. Among the designed diversity, the compounds 5k, 5n and 5o were found significantly active in primary anti-tuberculosis assay at minimum inhibitory concentration <6.25 μ m. Moreover, the IC50 values of 5k and 5o in level-2 screening were observed as >10 μg/mL and 3.63 μg/mL, respectively. Design and synthesis of more focused library and its three-dimensional quantitative structure activity relationship analysis are underway. [ABSTRACT FROM AUTHOR]

Abstract: Control and prevention of tuberculosis is a major challenge, as one-third of the world’s population is infected with Mycobacterium tuberculosis. The resurgence of tuberculosis and the emergence of multidrug-resistance strains of mycobacteria, necessitate the search for new class of antimycobacterial agents. As a part of investigation of new antitubercular agents in this laboratory, we describe the syntheses of various hydrazides of comarins, quinolones and pyrroles and screening against M. tuberculosis (Mtb) H37Rv by using rifampin as a standard drug. Among the designed molecules, the most prominent compounds 2a–g, 4a and 9a showed >90% GI at MIC<6.25μg/mL. Finally, these studies suggests that compounds 2a–g, 4a and 9a may serve as promising lead scaffolds for further generation of new anti-TB agents. [Copyright &y& Elsevier]

Abstract: A small library of 2-indolinone derivatives with the 2,6-dichlorophenyl ring at the N1 position and with varying substitutions including aryl groups at the 3-position were synthesized, and their structures were confirmed by spectral analysis. All molecules were screened for their in vitro cytotoxic activity on SW620 colon cancer cell lines. Among the designed series compounds 4c, 4f and 4j were found to be active at concentrations of 2–15μg/ml. Some 3D-QSAR models were also built to understand the structure–activity relationship. [Copyright &y& Elsevier]

Abstract: A set of 25 coumarin-4-acetic acid benzylidene hydrazides were synthesized and characterized by NMR, IR and mass spectroscopic techniques. The compounds were evaluated for their anti-tubercular activity against Mycobacterium tuberculosis H37Rv strain using the BACTEC 460 system to determine percentage inhibition. To understand the relationship between structure and activity, a 3D-QSAR analysis has been carried out by Comparative Molecular Field Analysis (CoMFA). Several statistically significant CoMFA models were generated. The CoMFA model generated with database alignment was the best in terms of overall statistics. The CoMFA contours provide a good insight into the structure activity relationships of the compounds reported herein. [Copyright &y& Elsevier]

Abstract: Present study and investigations reveals that, the hydrazones of 3-acetyl-4-hydroxycoumarin undergo ring cyclization to give, 3-methyl-1-substituted phenyl-1H-chromeno[4,3-c]pyrazol-4-ones (2a–m) under the influence of microwave irradiation and by using Zn[l-proline]2, a novel Lewis acid catalyst. The overall yields of the products were found to be 82–93%. Without use of the catalyst, no reaction progress was observed. No significant changes in the overall yields of the products were observed at high microwave power and at high temperatures. The reusability of the catalyst was also checked and found up to seven cycles. [Copyright &y& Elsevier]

The required title reagent (III) is readily available in one pot and excellent yield and can be applied with success to the olefination of a variety of aliphatic and aromatic aldehydes under either conditions A) or B). [ABSTRACT FROM AUTHOR]

Using in-situ prepared LiNK reagent, methylarenes are sequentially converted into mono- and bis-trimethylsilylated derivatives. [ABSTRACT FROM AUTHOR]

A new general two-step approach for the synthesis of bench-stable α,α-bis(trimethylsilyl)toluenes and tris(trimethylsilane) is developed. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is the group of Donal F. O'Shea at the Royal College of Surgeons in Ireland. The image depicts the facade of the original building of the Royal College of Surgeons in Ireland, which has housed the chemistry department since its foundation in 1828. Read the full text of the article at . [ABSTRACT FROM AUTHOR]

Peterson olefination as represented by the building facade is one of the historic yet still essential building blocks of synthetic chemistry. In their Communication on page 8737 ff., D. O'Shea et al. report on the first stereoselective aza ‐ Peterson reaction utilising bench stable geminal bis ‐ silane reagents with imine substrates. These advances have allowed several long ‐ standing limitations for this double bond forming reaction to be overcome. The facade itself is the entrance into the original building of the Royal College of Surgeons in Ireland which has housed the chemistry department since its foundation in 1828. [ABSTRACT FROM AUTHOR]

Review: [53 refs. [ABSTRACT FROM AUTHOR]

Review: [43 refs. [ABSTRACT FROM AUTHOR]

Review: 233 refs. [ABSTRACT FROM AUTHOR]

The article presents the steps of the chemical reactions in access of trisubstituted purines via sequential regioselective mitsunobu coupling.

Ruthenium-catalyzed direct arylations of phenols bearing removable directing groups were accomplished through carboxylate assistance via six-membered ruthenacycles as key intermediates. [ABSTRACT FROM AUTHOR]

The resurgence of tuberculosis and the emergence of multidrug-resistant strains of Mycobacteria necessitate the search for new classes of antimycobacterial agents. We have synthesized a small library of 50 analogues of 4-(arylamino)coumarins with various aromatic amines at the C4- position of the coumarin scaffold. The compounds were evaluated for antimycobacterial activity against Mycobacterium tuberculosis H37Rv with rifampicin as the standard. Of the molecules synthesized, compound 9 was found to be most potent with a minimum inhibitory concentration >6.25 μg/mL for 100% inhibition. In an effort to develop new and more effective molecules in this series, the relationship between structure and activity was investigated by comparative molecular field analysis. Various models were generated using comparative molecular field analysis alone and comparative molecular field analysis plus a hydropathy field (HINT). In all, eight models were generated with atom-fit and field-fit alignment strategies. The comparative molecular field analysis models (Models 3a and 4a) based on field-fit alignment were the best with statistically good correlation coefficients ( r2) and cross-validated q2. The values of r2pred for the validation set were 0.469 and 0.516. Based on the comparative molecular field analysis contours, some insights into the structure-activity relationship of the compounds could be gained. [ABSTRACT FROM AUTHOR]

The present investigation deals with the rapid microwave-assisted synthesis of compounds containing fused bicyclic systems. Dihydropyrimidines obtained via a microwave-assisted Biginelli reaction were treated with dibromo alkanes under microwave conditions to yield thiazolo-pyrimidine and pyrimido-thiazine systems. The usefulness of this method lies in carrying out the reaction without a catalyst and solvent in a shorter time. The reaction was successfully extended to develop fused systems from benzimidazole-2-thiol. [ABSTRACT FROM AUTHOR]

Abstract: 1,5-Benzothiazepine and 1,5-benzodiazipine are the two main seven-membered heterocyclic ring systems reported for their cardiac and psychotherapeutic activities. Successful introduction of diltiazem and clentiazem for angina pectoris, hypertension, arrhythmias and other related cardiac disorders proved potential of 1,5-benzothiazepine moiety. Subsequently 1,5-benzodiazepines were highlighted as important biologically active scaffolds. Also, discovery of thiazesim and quetiapine fumarate as psychotropic agents attracted much attention worldwide. The current review article focuses on pharmacological profile associated with 1,5-benzodiazepines. This article mainly covers structural modifications done for various targets along with the brief description of the targets. [Copyright &y& Elsevier]

An efficient synthesis of 4 H,5 H,6 H,9 H-pyrido[ ij]pyrano[3,2- c]quinolines 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4j, 4k, 4l, 4m, 4n, 4o, 4p, 4q, 4r, 4s, 4t as well as spiro compound 6 was achieved via multicomponent approach by using DBU as a catalyst under the remarkably mild reaction conditions. The structures of the compounds were characterized by 1H NMR, 13C NMR, and mass spectral analysis. An attractive feature of this inexpensive protocol includes facile synthesis, shorter reaction time, ease of work-up, large number of functional group tolerance, and good to excellent yields with high purity. [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "DBU-Catalyzed Multicomponent Synthesis: Facile Access of 4,5,6,9-Tetrahydro-pyrido[3,2-c]quinolines" by R. Chaniyara and others, published in the "Journal of Heterocyclic Chemistry" in 2014.