Alkylation

adduct specific for DEB, PYRV, requires-due to its tertiary amine structure-other techniques. The reaction products were identified by GC/MS, PYRV by 13C and 'H NMR, and THBV because of its formation by reduction of the Schiff bases of threose and erythrose with hemoglobin.

3-Methyladenine DNA glycosylase (AlkD) belongs to a new family of DNA glycosylases; it initiates repair of cytotoxic and promutagenic alkylated bases (its main substrates being 3-methyladenine and 7methylguanine). The modification of the comet assay (single cell gel electrophoresis) using AlkD enzyme thus allows assessment of specific DNA alkylation lesions. The resulting baseless sugars are alkali-labile, and under the conditions of the alkaline comet assay they appear as DNA strand breaks. The alkylating agent methyl methanesulfonate (MMS) was used to induce alkylation lesions and to optimize conditions for the modified comet assay method with AlkD on human lymphoblastoid (TK6) cells. We also studied cellular and in vitro DNA repair of alkylated bases in DNA in TK6 cells after treatment with MMS. Results from cellular repair indicate that 50% of DNA alkylation is repaired in the first 60 min. The in vitro repair assay shows that while AlkD recognises most alkylation lesions after 60 min, a cell extract from TK6 cells recognises most of the MMS-induced DNA adducts already in the first 15 min of incubation, with maximum detection of lesions after 60 min' incubation. Additionally, we tested the in vitro repair capacity of human lymphocyte extracts from 5 individuals and found them to be able to incise DNA alkylations in the same range as AlkD. The modification of the comet assay with AlkD can be useful for in vitro and in vivo genotoxicity studies to detect alkylation damage and repair and also for human biomonitoring and molecular epidemiology studies.

Cross-coupling reactions of 2-amino-6-chloro-9-{2-[(diisopropoxyphosphoryl)methoxy]-ethyl}purine (1) and 2-amino-9-{2-[(diisopropoxyphosphoryl)methoxy]ethyl}-6-iodopurine (2) with diverse types of organometallic reagents have been studied. Arylboronic acids reacted with 1 to give the corresponding 2-amino-6-arylpurines 3a-3d in good yields. Analogously, trialkylaluminium reagents were used for the preparation of 6-alkyl-2-aminopurines 3k and 3l from 1. Hetarylzinc halides and hetarylstannanes required the use of 2-amino-6-iodopurine 2 to give the corresponding 2-amino-6-hetarylpurines 3e-3j in fair to good yields. A CuI/KF mediated coupling of perfluoroalkylsilanes with 2 afforded the 2-amino-6-perfluoroalkylpurines 3m and 3n in moderate yields. Cleavage of the esters 3 with bromo(trimethyl)silane gave the target free phosphonates 4 that were purified by ionexchange chromatography. The title compounds were tested on antiviral and cytostatic activity.

A new series of thiophene containing triarylmethane derivatives were synthesized from the Friedel-Crafts alkylation of diarylcarbinols followed by incorporation of amino alkyl chains. These were evaluated against Mycobacterium tuberculosis H 37 R v and showed the activity in the range of 3.12-12.5 lg/mL in vitro.

A direct tetraalkylation of thiacalix[4]arenes using procedures well established in ÔclassicalÕ calixarene chemistry usually gives the 1,3-alternate conformers as the main product (n-PrI/K 2 CO 3 /acetone) while the cone conformers are obtained only in very poor yields (n-PrI/NaH/DMF). Surprisingly, the so far almost inaccessible cone conformers can be prepared in high yields using the two-step procedure: dialkylation-dialkylation, opening the way for their further utilisation in supramolecular chemistry.

tert-Butylanilines are used in pharmaceuticals, pesticides, plastics, additives and dyes. They are usually prepared by reacting aniline in presence of liquid acid catalysts with pure isobutylene or C 4 fraction from naphtha crackers containing isobutylene. These processes suffer from problems of use of highly corrosive liquid acids and also the source of isobutylene. Both C-and N-alkylation are possible in the case of aniline depending on reaction conditions such as temperature, source of isobutylene and type of catalyst. In the current study, several solid acids, majority of which were heteropolyacids (HPAs) supported on different clays, were evaluated with both methyl tert-butyl ether (MTBE) and tert-butanol as alkylating agents in a pressure reactor under autogenous pressure.

Notes, Brief Communications, and JOCSynopses have length limits. The abstract, introductory remarks, and results and discussion of a Note do not exceed 3000 words; the limit for a Brief Communication is 2000 words. For Notes and Brief Communications, tables and graphics (figures, reaction schemes, and chemical structure graphics) are counted against the word-count limits at the rate of 50 words per vertical inch for one-column (<3.3 inches wide) items, and 100 words per vertical inch for wider items. There are no word-count limits on the experimental section. For information about the length limit for JOCSynopses see section 2.3.3.

A facile method for the alkylation of fluorene achieved via direct C-H alkylation under aqueous conditions is reported, wherein the formation of fluorenone is inhibited, resulting in the exclusive formation of the desired dialkyl-substituted fluorene monomer. As a proof of concept, this method has also been successfully extended to perform N-alkylation of carbazole, diphenylamine, and N,N-dialkylation of aniline in high yields.

Introduction: We developed a new fully automated method for the radiosynthesis of [ 18 F]fluorocholine by modifying the commercial 2-[ 18 F]fluoro-2-D-deoxy-glucose ([ 18 F]FDG) synthesizer module (GE TracerLab MX, formerly Coincidence). Methods: [ 18 F]Flurocholine was synthesized by 18 F-fluoroalkylation of N,N-dimethylaminoethanol using [ 18 F]fluorobromomethane as fluoromethylating agent. [ 18 F]Fluorobromomethane was produced by reaction of dibromomethane with [ 18 F]fluoride, assisted by Kryptofix 2.2.2. Results: After purification on solid-phase extraction cartridges, the [ 18 F]fluorocholine was obtained in 15-25% radiochemical yields (decay not corrected), with more than 99% radiochemical purity. Specific activity was more than 37 GBq/μmol. Synthesis time was less than 35 min. Conclusion: This new automated synthesis technique provides high and reproducible yields that could be dedicated for routine use with the same [ 18 F]FDG disposable cassette system.

The current work utilizes the ab initio density functional theory (DFT) to develop a molecular level of the mechanistic understanding on the phenol alkylation in the presence of a cation-exchange resin catalyst, Amberlyst-15. The catalyst is modeled with the benzene sulfonic acid, and the effect of this acid on olefins such as isopropene (i-Pr) and tributene (t-Bu) in a phenol solution mimics the experimental condition. A neutral-pathway mechanism is established to account for early-stage high concentration of the phenolic ether observed in experiments. The mechanism involves an exothermic reaction between olefin and the benzene sulfonic acid to form ester followed by three reaction pathways leading to direct O-alkylation, o-C-alkylation, and p-C-alkylation. Our calculations conclude that O-alkylation to form the phenolic ether is the most energetically favorable in the neutral condition. An ionic rearrangement mechanism describes intramolecular migrations of the alkyl group from the phenolic ether to form C-alkylphenols, while the positively charged protonation significantly lowers transition barriers for these migrations. The ionic rearrangement mechanism accounts for high yields of o-C-alkylphenol and p-C-alkylphenol. Competition between the H atom and the alkyl R group at the substitutive site of the protonated ortho configuration is found to be the determining factor to the ortho/para ratio of C-alkylation products.

Coumarins, also known as benzopyrones, are present in remarkable amounts in plants, although their presence has also been detected in microorganisms and animal sources. The structural diversity found in this family of compounds led to the division into different categories, from simple coumarins to many other kinds of policyclic coumarins, such as furocoumarins and pyranocoumarins.

in 1998. He commenced his Ph.D. studies on the synthesis of N-methylamino acids in the same group in 1999. He is currently finalizing the writing and submission of his Ph.D. thesis. His current research interests are focused on the synthesis of modified peptides and peptide fragments with the aim to enhance in vivo stability via N-methylation and other related modifications. Luigi is a founding partner in Peptide Solutions Pty Ltd, a start-up company based on the research developed in his Ph.D. studies.

Due to environment and sustainability issues, this century has witnessed remarkable achievements in green technology in the field of materials science through the development of biocomposites. The development of high-performance materials made from natural resources is increasing worldwide. The greatest challenge in working with natural fiber reinforced plastic composites is their large variation in properties and characteristics. A biocomposite's properties are influenced by a number of variables, including the fiber type, environmental conditions (where the plant fibers are sourced), processing methods, and any modification of the fiber. It is also known that recently there has been a surge of interest in the industrial applications of composites containing biofibers reinforced with biopolymers. Biopolymers have seen a tremendous increase in use as a matrix for biofiber reinforced composites. A comprehensive review of literature (from 2000 to 2010) on the mostly readily utilized natural fibers and biopolymers is presented in this paper. The overall characteristics of reinforcing fibers used in biocomposites, including source, type, structure, composition, as well as mechanical properties, will be reviewed. Moreover, the modification methods; physical (corona and plasma treatment) and chemical (silane, alkaline, acetylation, maleated coupling, and enzyme treatment) will be discussed. The most popular matrices in biofiber reinforced composites based on petrochemical and renewable resources will also be addressed. The wide variety of biocomposite processing techniques as well as the factors (moisture content, fiber type and content, coupling agents and their influence on composites properties) affecting these processes will be discussed. Prior to the processing of biocomposites, semi-finished product manufacturing is also vital, which will be illustrated. Processing technologies for biofiber reinforced composites will be discussed based on thermoplastic matrices (compression molding, extrusion, injection molding, LFT-D-method, and thermoforming), and thermosets (resin transfer molding, sheet molding compound). Other implemented processes, i.e., thermoset compression molding and pultrusion and their influence on mechanical performance (tensile, flexural and impact properties) will also be evaluated. Finally, the review will conclude with recent developments and future trends of biocomposites as well as key issues that need to be addressed and resolved.

A series of soft quaternary ammonium antimicrobial agents, which are analogues to currently used quaternary ammonium preservatives such as cetyl pyridinium chloride and benzalkonium chloride, were synthesized. These soft analogues consist of long alkyl chain connected to a polar headgroup via chemically labile spacer group. They are characterized by facile nonenzymatic and enzymatic degradation to form their original nontoxic building blocks. However, their chemical stability has to be adequate in order for them to have antimicrobial effects. Stability studies and antibacterial and antiviral activity measurements revealed relationship between activity, lipophilicity, and stability. Their minimum inhibitory concentration (MIC) was as low as 1 µg/mL, and their viral reduction was in some cases greater than 6.7 log. The structure-activity studies demonstrate that the bioactive compounds (i.e., MIC for Grampositive bacteria of <10 µg/mL) have an alkyl chain length between 12 and 18 carbon atoms, with a polar headgroup preferably of a small quaternary ammonium group, and their acquired inactivation half-life must be greater than 3 h at 60°C.

From the initial development of a homologous MoritaeBayliseHillman reaction utilizing epoxides as electrophiles, the method was expanded to enable the exclusively organocatalyzed intramolecular allylation of enones and to develop the intramolecular MBH-type alkylation of activated alkenes. We successfully utilized both enones and unsaturated thioesters as the activated alkene component. This work, carried out using stoichiometric amounts of the trialkylphosphine, gave an array of functionalized fiveand six-membered carbocycles in high yields. With the cycloalkylation of enones and thioesters, conditions that allowed the use of substoichometric amounts of the phosphine catalyst were developed. As a result both fiveand six-membered rings can be formed efficiently with little to no loss in yield upon comparison to yields obtained when stoichiometric amounts of trialkylphosphines were employed. We isolated, for the first time, an MBH-type intermediate exhibiting unprecedented trans geometry of the phosphonium salt and acyl group.

Stereoselective total syntheses of two novel conformationally restrained epothilone analogues are described. Evans asymmetric alkylation, Brown allylation, and a diastereoselective aldol reaction served as the key steps in the stereoselective synthesis of one of the two key fragments of the convergent synthetic approach.Enzyme resolution was employed to obtain the second fragment as a single enantiomer. The molecules were assembled by esterification, followed by ring-closing metathesis. In preliminary cytotoxicity studies, one of the analogues showed strong and selective growth inhibitory activity against two leukemia cell lines over solid human tumor cell lines. The precise biological mechanism of action and high degree of selectivity of this analogue remain to be examined.

Various alkylarenes were oxidized to the corresponding aryl carboxylic acids using aqueous potassium permanganate under heterogeneous condition in the presence of hydrodynamic cavitation and the results of the reaction have been compared with the acoustic cavitation in terms of their energy efficiency. The rate of reaction was determined for each reaction. In the oxidation of p-xylene, seven times more product could be obtained in the case of hydrodynamic cavitation than in the case of acoustic cavitation. The reaction was found to be considerably accelerated at ambient temperature.

The need for alternative energy sources that combine environmental friendliness with biodegradability, low toxicity, renewability, and less dependence on petroleum products has never been greater. One such energy source is referred to as biodiesel. This can be produced from vegetable oils, animal fats, microalgal oils, waste products of vegetable oil refinery or animal rendering, and used frying oils. Chemically, they are known as monoalkyl esters of fatty acids. The conventional method for producing biodiesel involves acid and base catalysts to form fatty acid alkyl esters. Downstream processing costs and environmental problems associated with biodiesel production and byproducts recovery have led to the search for alternative production methods and alternative substrates. Enzymatic reactions involving lipases can be an excellent alternative to produce biodiesel through a process commonly referred to alcoholysis, a form of transesterification reaction, or through an interesterification (ester interchange) reaction. Protein engineering can be useful in improving the catalytic efficiency of lipases as biocatalysts for biodiesel production. The use of recombinant DNA technology to produce large quantities of lipases, and the use of immobilized lipases and immobilized whole cells, may lower the overall cost, while presenting less downstream processing problems, to biodiesel production. In addition, the enzymatic approach is environmentally friendly, considered a "green reaction", and needs to be explored for industrial production of biodiesel.

Levulinic acid (LA) is one of the most promising biomass-derived platform chemicals owing to its wider convertibility to a large number of commodity chemicals. Numerous LA derivatives have paramount importance in the global economy. In this article, we have comprehensively reviewed various processes that have been developed to produce LA and its derivatives from different sugars and cellulosic feedstocks. These designs are discussed in order to provide comparative information on their chemical mechanisms, process merits, demerits, and scale-up potentials. Monosaccharides such as fructose, glucose, and xylose, and disaccharides such as sucrose are good feedstocks for LA production with Brønsted or Lewis acids as the catalysts in either homogenous or heterogeneous reaction systems. LA yield is in the range of 2-90%, which is greatly dependent on the reaction conditions. Polysaccharides such as cellulose and even lignocellulose are also employed for LA production. Brønsted acids, especially mineral acids, appear to be more efficient than Lewis acids to catalyze the conversion of polysaccharides and lignocellulosic biomass to LA. The important LA derivatives and their preparation reactions such as aminolevulinic acid, diphenolic acid, γ-valerolactone, various alkyl esters, and valerate have also been reviewed. These derivatives have extended utilization in modern industries due to the emergent environmental concerns. Furthermore, the challenges arising during these lab-scale processes are critically unveiled to pave the way for process selection and scale-up study for the production of LA and different derived chemicals. It has been recommended that to improve the production efficiency of LA and its derivatives, efforts should be made to develop robust catalysts and reaction systems in order to improve the reaction selectivity. The mechanisms of LA formation from various feedstocks are also significantly important to guide the intensification of the process. Reactors with potential of industrial application are one of the crucial steps for the scaling up of LA production.

Chiral hydantoin (S)-1 was prepared in good yield from phenyl isocyanate and N-[(S)-aphenylethyl]glycinate, (S)-3. Enolate (S)-1-Li was methylated in high yield and good diastereoselectivity. In contrast, a second alkylation reaction of methylated enolate (S)-4-Li proceeded with essentially no diastereoselectivity. Nevertheless, dialkylated hydantoins, (S,S)-7 and (S,R)-7, could be readily separated by¯ash chromatography and subsequent hydrolysis of either derivative afforded the desired (S)-L-amethyldopa or (R)-D-a-methyldopa in good yield.

Dimeric anthracenyldimethyl-derived Cinchona ammonium salts are used as chiral organocatalysts in 5 mol% for the phase-transfer enantioselective alkylation reaction of 2alkoxycarbonyl-1-indanones with activated bromides. The corresponding adducts bearing a new all-carbon quaternary center are obtained usually in high yield and with moderate and opposite enantioselectivity (up to 55%) when using ammonium salts derived from quinidine and its pseudoenantiomer quinine as organocatalysts. These catalysts can be almost quantitatively recovered by precipitation in ether and reused.

Processes for the production of xylenes, which occur in an integrated aromatic complex, are discussed. A brief overview of the work carried out at Indian Petrochemicals Corporation Limited for the development of zeolite-based catalytic processes for the production of aromatics is presented. This includes xylene isomerization, transalkylation and disproportionation of C7 and C9 aromatics for maximization of xylenes, selective disproportionation of toluene and selective alkylation of mono-alkylaromatics to p-dialkylbenzene. Achievements in the commercialization of zeolite-based catalysts and processes for isomerization of m-xylene to p- and o-xylene along with dealkylation of ethylbenzene, and for selective ethylation of ethylbenzene to produce p-diethylbenzene are highlighted.

The present paper deals with the synthesis and characterization of metal complexes of Schiff base derived from xipamide, a diuretic drug. The bidentate ligand is derived from the inserted condensation of 5-aminosulfonyl-4-chloro-N-2,6-dimethyl phenyl-2-hydroxybenzamide (Xipamide) with salicylaldehyde in a 1 : 1 molar ratio. Using this bidentate ligand, complexes of Hg(II), Zn(II), and VO(IV) with general formula ML 2 have been synthesized. The synthesized complexes were characterized by several techniques using molar conductance, elemental analysis, magnetic susceptibility, FT-IR spectroscopy, electronic spectra, mass spectra, and particle size analysis. The elemental analysis data suggest the stoichiometry to be 1 : 2 [M : L]. All the complexes are nonelectrolytic in nature as suggested by molar conductance measurements. Infrared spectral data indicate the coordination between the ligand and the central metal ion through deprotonated phenolic oxygen and azomethine nitrogen atoms. Spectral studies suggest tetrahedral geometry for Hg(II), Zn(II) complexes, and square pyramidal geometry for VO(IV) complex. The pure drug, synthesized ligand, and metal complexes were screened for their antifungal activities against Aspergillus niger and Aspergillus flavus. The ligand and its Hg(II) and VO(IV) complexes were screened for their diuretic activity too.

Attempts toward the asymmetric synthesis of (À)-tetrahydrolipstatin are described. A palladium catalyzed Wacker-type reaction to convert an alkene to a ketone, highly diastereoselective reduction of a b-hydroxy ketone, selective oxidation of a diol, and modular synthesis are the key features of the successful approach.

An enantioselective, convergent total synthesis of the antiviral marine natural product (-)-hennoxazole A is completed in 14 steps (longest linear sequence) from commercially available 4-methyloxazole-2carboxylic acid. Synthesis of the C 1 -C 15 pyran/bisoxazole fragment takes advantage of an aldol-like coupling between a dimethyl acetal and an N-acetylthiazolidinethione for the direct, stereoselective installation of the C 8 -methoxy-bearing stereocenter. A one-pot acetoacetate acylation/decarboxylation/ cyclodehydration of another elaborate thiazolidinethione allows for rapid assembly of the pyran-based ring system. Synthesis of the C 15 -C 25 skipped triene side chain fragment makes use of a [2,3]-Wittig-Still rearrangement for efficient installation of the trisubstituted Z-double bond. Key late-stage coupling of the two fragments is effected by deprotonation of the methyl group on the bisoxazole system using lithium diethylamide, followed by alkylation with an allylic bromide side chain segment to form the C 15 -C 16 bond.

BACKGROUND: Alkylation of o-cresol with propylene or isopropyl alcohol (IPA) over solid acid catalysts results in the formation of carvacrol, which finds potential applications in the synthesis of fine chemicals, intermediates, specialty chemicals, flavours and fragrances.

Absorption of isobutylene in p-cresol to prepare butylated hydroxytoluene (BHT), an important antioxidant, has been studied by using solid sulfated zirconia. Absorption is accompanied by complex chemical reactions. Detailed theoretical and experimental analysis of this system is reported here, and kinetic parameters have been established. Effects of various parameters such as partial pressure of isobutylene, catalyst loading, particle size, and temperature on the rates of reaction have been analyzed.

This paper describes the design of the highest affinity ligands for Grb2 SH3 domains reported so far. These compounds were designed by combining N-alkyl amino acid incorporation in a proline-rich sequence with subsequent dimerization of the peptoid sequence based on structural data and molecular modeling. Optimization of the linker size is discussed, and the N-alkyl amino acid incorporation into both monomeric halves is reported. Because the affinity for Grb2 of the optimized compounds was too high to be measured using the fluorescent modifications that they induce on the Grb2 emission spectrum, a competition assay was developed. In this test, Grb2 is pulled down from a cellular extract by the initial VPPPVPPRRR peptide bound to Sepharose beads. In the presence of competitors, the test quantifies the amount of Grb2 displaced from the beads. It has enabled us to determine a K i value in the 10 -10 M range for the highest affinity Grb2 peptoid analogue dimer.

In this review paper, information about amine compounds, methods of synthesis, reactions, properties, stability, using as catalysis in various reactions in most of organic reactions, test, reactions which containing amine compounds, properties, applications.

Monoalkylation of primary amines using amine hydrobromides and alkyl bromides has been carried out. Under controlled reaction conditions the reactant primary amine was selectively deprotonated and made available for reaction, while the newly generated secondary amine remained protonated, and did not participate in alkylation further. Reaction was carried out under mild reaction conditions and was applicable to a wide range of primary amines and alkyl bromides.

Coumarins, also known as benzopyrones, are present in remarkable amounts in plants, although their presence has also been detected in microorganisms and animal sources. The structural diversity found in this family of compounds led to the division into different categories, from simple coumarins to many other kinds of policyclic coumarins, such as furocoumarins and pyranocoumarins.

N-methyl imidazole, pyridine and triethylamine based Bronsted acidic ionic liquids with sulfonic acid (–SO3H) functionality were obtained using 1,4-butane sultone. They were tested in a batch reactor for catalytic activity in the tert-butylation of phenol with tert-butyl alcohol (TBA). The reaction time, reaction temperature and reactant mole ratio were optimized. Among the three ionic liquids, triethylammonium based sulfonic acid functionalized ionic liquid was found to be the most promising and gave the highest phenol conversion. A maximum phenol conversion of 86% with 57.6% selectivity to 4-tert-butylphenol (4-TBP) was achieved at a temperature of 70 °C at a low ionic liquid to phenol ratio. The catalyst retained its activity even after 5 recycles. A kinetic model was developed for the reaction mechanism based on the product distribution and the kinetic parameters were estimated. The activation energy for ionic liquid catalyzed alkylation of phenol was found to be 11.13 kcal/mol in the temperature range of 50–90 °C. Negative activation energy was observed for 2-tert-butylphenol (2-TBP) to 2,4-di-tert-butylphenol (2,4-DTBP) and the extended Arrhenius equation was used to interpret this trend.

The first enantioselective total synthesis of (-)-8-deoxyserratinine has been achieved in 15 steps from enone 4 with 7% overall yield. The key features include a highly efficient Helquist annulation to furnish the cis-fused 6/5 bicycle, facile construction of the aza nine-membered ring system employing double N-alkylation strategy, as well as asymmetric Shi epoxidation, delivering the desired -epoxide stereospecifically.

The route selection and development of a convenient synthesis of 4-carboxy-4anilidopiperidines is described. Previous routes were hampered by the low yield of the target esters as well as the inability to convert the esters to the required free acids. Considerations for large-scale production led to a modified synthesis that utilised a tert-butyl ester of 4-carboxy-4-anilidopiperidines which resulted in a dramatic increase in the overall yield of the target N-propionylated-4-anilidopiperidine-4-carboxylic acids and their corresponding methyl esters. These compounds are now available for use as precursors and reference standards, of particular value for the production of 11 C and 18 F-labelled 4-carboxy-4-anilidopiperidine radiotracers.

General synthetic methods for the preparation of dialkylamines3 are usually included in some of these three strategies: reductive amination of aldehydes and ketones,4 alkylation of primary amines with alkyl halides,5 and alkylation reactions using transition metals.6 All of them ...

Base excision repair (BER) pathway executed by a complex network of proteins is the major system responsible for the removal of damaged DNA bases and repair of DNA single strand breaks (SSBs) generated by environmental agents, such as certain cancer therapies, or arising spontaneously during cellular metabolism. Both modified DNA bases and SSBs with ends other than 3'-OH and 5'-P are repaired either by replacement of a single or of more nucleotides in the processes called short-patch BER (SP-BER) or long-patch BER (LP-BER), respectively. In contrast to Escherichia coli cells, in human ones, the two BER sub-pathways are operated by different sets of proteins. In this review the selection between SP-and LP-BER and mutations in BER and end-processors genes and their contribution to bacterial mutagenesis and human diseases are considered.

Treatment of calix[4]arenes 1 with a large excess of 2-(chloromethy1)pyridine hydrochloride in NJVdimethylformamide produced tetrakis [ (2-pyridylmethyl)oxy]calix[4]arenes (2) in a fixed cone conformation. When lower calix[4]arene:2-(chloromethyl)pyridine molar ratios (1:4) were used, regioselective proximal disubstitution at the phenolic oxygens (lower rim) was realized in good yield.