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The synthesis, phase-transfer catalysis and the recycling of the several Perfluoroalkylated 4,13-diaza-18-crown-6 ethers, having two different side arms are studied. The analysis reveals that the perfluoroalkylated macrocycles can be widely used as the phase-transfer catalysts, giving extremely high catalytic activities under solid-liquid phase transfer conditions.

The kinetics of the reactions of various primary and secondary amines with the benzhydrylium ions in water are investigated, demonstrating their nucleophilcites. The results show a poor correlation between the nucleophilicities values, as the secondary alkyl amines and anilines are more nucleophilicdue to the difference in their pH values.

The reactions of N-chlorotaurine with several nucleophilic reagents, the protonation at nitrogen during the transfer of chlorine from N-chlorotaurine to a nucleophile and its mechanisms of transfer reactions are studied. The results have provided evidence against an electron-transfer mechanism for chlorination of the nuclophiles by protonated N-chlorotaurine.

A short, two-step approach based on a Ugi multicomponent reaction (MCR) followed by a subsequent intramolecular [S.sub.N]2 reaction is described for the synthesis of diazepane or diazocane systems. The results have shown the power of coupling Ugi MCRs with post-condensation transformations for obtaining relatively complex heterocyclic scaffolds in few steps.

A series of archetypal [S.sub.N]2@C and [S.sub.N]2@Si reactions are analyzed by using the ADF program. The results have shown that by simple increasing the steric demand of the substituents R around the silicon atom, the [S.sub.N]2@Si mechanisms changes from its regular single-well potential energy surfaces (PES), via a triple-well PES, to a double-well PES, which is normally encountered for [S.sub.N]2@C reactions.

A study conducted reports that triflyl azide rapidly reacts with a series of amine-functionalized solid supports to generate azide-coated supports. The results show that the so-formed azide coat could be used to load leader nucleoside monomers on solid supports using click chemistry under benign experimental conditions.

The nucleophilic addition of beta-lactam-4-ylidenes, a type of ambiphilic cyclic amidocarbene, to aryl isocyanates is studied and their application in organic syntheis is demonstrated. It is reported that beta-lactam-4-ylidenes, actually behave as good nucleophiles as bisheteroatom-substituted carbenes in the addition reaction to isocyanates to form both N- and O-lactam substituted spiro(azetidine-2-one-4,3'-indole-2'-one) derivatives.

The results from a thorough natural bond orbital analysis of several transition states (TSs) for nucleophilic additions to carbonyl function are discussed. It is demonstrated that the absence or presence of the Cieplax type [sigma]->[sigma.sup.*#] interaction depends on whether the TS in question is of early or late character.

The nucleophilic pentafluoroethylation reagent generated by reduction of pentafluoroethyl iodide by tetrakis(dimethylamino)ethylene (TDAE) is useful in their nucleophilic reactions with aldehydes, ketones, imines, disulfides and diselenides. Irradiation has proved to be very useful in the aldehyde and ketone reactions.

The reactivity of (2-azaallyl)nitriles toward double nucleophilic addition and the double allylation reactions of (2-azaallyl)stannanes are reported. The conversion of the N,N-bis(3-butenyl)amines obtained as products from the double allylation reactions to 2,3,6,7-tetrahydroazepines through ring-closing metathesis is described.

Full details of the theoretical study are reported on the lithium--halogen reaction of 1,1-dihaloalkenes with methyllithium and the nucleophilic substitution reaction of the resulting alpha-halo alkenyllithium compounds. The thermodynamic preferences were predicted correctly by the energy differences of the products.

1,3-Dinitrodibenz[b,f][1,4]oxazepin-11(10H)-one, prepared by intramolecular displacement of nitro group in N-(2-hydroxyphenyl)-2,4,6-trinitrobenzamide, reacts with O- and S-nucleophiles to yield the products of mono-or bis-substitution of the nitro group. N-Alkylation of the nitro substituted dibenz[b,f][1,4]oxazepin-11(10H)-ones yields analogues of a known antidepressant drug Sintamil.

Ab calculations are used to study the S(sub N)2 reactions of the CH3OCH2I with a methoxide ion (CH(sub 3)O(super -) and a methanol molecule by systematically building the reaction system with explicit incorporation of the methanol solvent molecules. The result suggest that molecule S(sub N)2 reaction could be very fast in methanol solutions through reaction with the methanol tetramer.

Conformationally restrained substituted pregnane-20-one derivatives are obtained by an intramolecular nitrene and dition onto a C-5/C-6 double bond involving a tethered C-19 sulfamoyl moiety. The resulting aziridine underwent regioselective nucleophilic ring opening at C-5 at room temperature with cyanide, fluoride, and acetate.

A series of gas-phase nucleophilic substitution reactions at sulfur of methanesulfinyl derivatives by small anions is examined by Hartree-Fock, MP2, and DFT computations. In most cases, substitution is found to follow an addition-elimination mechanism, resulting in a triple-well potential energy surface with small barriers of activation on either side of the central, tetracoordinate-sulfur minimum.

A study of the denitrosation mechanism of N(super 1)-nitrosomelatonin (NOMe1) as a model for N(super 1)-nitrosoindoles is presented. The results revealed that NOMe1 slowly decomposes spontaneously in aqueous solution, generating melatonin as the main organic product.

The extension of carbocyclizations of C-tethered N-acyloxyiminium ions with substituted alkene, alkyne and allene tethers to give novel azacyclic ring systems is reported. It is shown that the carbocyclization of mixed allene/alkene/alkyne tethers favors reaction of the allene, leading to the preferential formation of relatively strained hydrooxazinones rather than the corresponding hydroindoles.

The scope and limitations of the CF3I/TDAE reagent in nucleophilic trifluoromethylation chemistry is studied. It is demonstrated that a two-electron transfer from TDAE to CF3I generates a stabilized TDAE dication/trifluoromethyl anion 'complex'.

The m-chloroperoxybenzoate (m-CPBA) anion is highly efficient nucleophilic epoxidating reagent for strongly deactivated olefins containing two electron-withdrawing groups at the same carbon, under mild conditions. It is observed that the combined use of m-CPBA with catalytic or stoichiometric amounts of KOH or K2CO3 allows the selection formation of oxirans only from strongly gem-disubstituted olefines by electron withdrawing agents.

A variety of key precursors to the intramolecular Diels-Alder reaction of furan diene (IMDAF) are prepared via a very facile 1,4-addition of O-, S-, N-, and C-entered nucleophiles possessing unsaturated tether to beta-furyl nitroethylene. Subsequent IMDAF reaction of the 1,4-adducts, carried out under thermal conditions, provided five- and six-membered carbocycles and heterocycles fused to an easily cleavable oxabicycloheptane moiety.

The viability of hydroxylamines as nucleophiles in transition-metal-catalyzed allylic substitution was examined. It was found that the oxygen atom of hydroxylamines having an N-electron-withdrawing substituent acts as a reactive nucleophile.

The synthesis of cis- and trans-3-(benzyloxymethyl)-1, 2-epoxycyclohexanes allows the study of their nucleophilic addition reactions. In the presence of a metallic salt catalyst, the cis-epoxide forms chelate intermediates which invite a nucleophilic attack on the C-1 oxirane carbon, resulting in ring cleavage. Its preference for chelation thus sterically directs the site of cleavage. The trans-epoxide, on the other hand, is prevented from undergoing chelation reactions due to its conformation. Its ring opening reactions are based on steric factors alone.

A unimolecular nucleophilic substitution (SN1) mechanism characterizes the reaction of N-(sulfonatooxy)-2-(acetylamino)fluorene with the aromatic amines, aniline and N,N-dimythelaniline. The observations on the kinetics and products of the reaction reveal the occurrence of an insubstantial overall rate effect and independent product yields. The study shows that the steric hindrance caused by the nitrogen in the fluorene compound apparently facilitates the alteration of the SN2 process leading to the development of the SN1 process.

The type of metal determines the synthetic route to be taken in nucleophilic organometallic reactions with 2-(1-naphthyl)- and 2-cinnamyl-1,3-oxazolidines. Organomagnesium reagents promote 1,4-conjugate addition while lithium, cerium and copper organometallic reagents facilitate 1,2-addition. Furthermore, the results have shown that organocerium reagents provide the most efficient 1, 2-addition to 2-substituted 1,3-oxazolidines. In addition, two 1,2-addition amino alcohol intermediates have been successfully converted to alpha-(1-naphthyl)alkylamines.

The highly reactive 2,3-dihalo-1-(phenylsulfonyl)-1-propenes can serve as precursors for the formation of different (phenylsulfonyl)methyl-substituted and annulated furans. The beta-dicarbonyl anions and the solvent that are introduced in the reaction influence the initial alkylation reaction's regiochemistry and the type of furan nucleus produced. Furthermore, the presence of 1,3-dicarbonyls at the C2-position completely reverses the manner of ring closure. The method can also be used in the preparation of functionalized cyclopentenones through the addition of beta-diketone and -keto ester anions to the dihalo propene.

The reaction of 1-(phenylsulfonyl)-1,2-propadiene with either bromine or iodine results in the formation of a highly reactive 2,3-dihalo-1-(phenylsulfonyl)-1-propene which features allyl halide, vinyl halide and vinyl sulfone functionalities at a three-carbon array. The nature and condition of the nucleophilic reactions determine the reactivity of the dihalo propene. Amines, thiophenols, sodium hydrides and ambident nucleophiles such as beta-dicarbonyls, silyl enol ethers and thioamides react with the dihalo propene to efficiently synthesize different arylsulfonyl-substituted heterocycles and furans.

The reactions of phenyl-substituted beta-nitrostyrenes with hydroxides and nitromethides in different Me2SO-water mixtures have been examined in order to determine the kinetics that characterize the nucleophilic addition. An increase in the resonance stabilization of substituted beta-nitrostyrenes results in a decrease in the equilibrium constants of hydroxide and nitromethide ions. In addition, the through resonance-induced preorganization of the electronic structure promotes a negative charge delocalization of the transitional state's nitro group and an increase in the reaction's intrinsic rate constant.

The ketones, (CF3)2C=O, CF3C(O)CF2Cl, CF3C(O)CF2H and (CF3 2 CF)2C=O, and several acid fluorides react with TMS-CF3 in the presence of an excess amount of F- in CH3CN to produce tertiary alkoxides in high yields. Subsequent acidification with sulfuric acid results in the conversion of the derived alkoxides to the corresponding alcohols. Furthermore, the application of the TMS-CF3 process allows the facile preparation of (CF3)3COH from either (CF3)2C=O or F2C=O.

The reaction of 10-(acetyloxy)- and 10-methoxy-3,4-dihydro-9(2H)-anthracene o-quinone methides with 2'-deoxyguanosine and -deoxyadenosine in H2O/CH3CN proceeds gradually and produces adequate amounts of intramolecularly stable adducts. The addition of deoxyguanosine and deoxyadenosine facilitates N(2) alkylation and N(6) alkylation, respectively. The H NMR spectroscopic analyses of the covalent adducts have identified the alkylation sites on both 2'-deoxynucleosides.

A study of the homologations of nortricyclanone, 8,9-didehydro-2-adamantone, bicyclo(3.1. 0)hexan-2-one and bicyclo(4.1.0)heptan-2-one shows that the Nozaki method for such ring expansions does not lead to retention of the functional group's conjugation. The method relies on initial nucleophilic attack of (dibromomethyl)lithium on the more accessible side of the carbonyl function. An analysis of the reactions suggests that competitive migration of the methylene with the cyclopropyl group leads to addition of a carbon atom to the ring.

An efficient method is described for preparing N-substituted 2H-1,4-benzoxazine-3-(4H)-ones from 2-halophenols via a nucleophilic substitution with 2-chloroacetamides followed by a CuI-catalyzed coupling cyclization. The method has involved simple reaction conditions, a short reaction time, and a broad substrate scope and it is useful for the efficient preparation of biologically and medicinally interesting molecules.

The development of an efficient synthetic route to new inherently chiral calix[4]arenes with an ABCD substitution pattern at the wide rim in the cone conformation is reported. The results highlight the beneficial effects of the multifunctional structure on its enantioselectivity as an organocatalyst in asymmetric Michael addition reactions.

A novel protocol for the annulation of tropone to enals involving nucleophilic heterocyclic carbene (NHC) catalyzed homoenolate formation was developed. The reaction led to bicyclic [delta]-lactones instead of the expected [gamma]-spirolactones, probably because of the uncommon [8+3] annulation pathway occurring via homoenolate.

The scope and limitation of the asymmetric nucleophilic aromatic substitution reaction of [alpha]-substituted 1,3-dicarbonyl compounds and activated aromatic systems catalyzed by N-benzyl-O-benzoylcinchoninium or cinchonidinium salts are presented. Various 1,3-dicarbonyl compounds and activated aromatic systems are evaluated for the aromatic nucleophilic substitution reaction, and it was found that the yield and enantioselectivity are very dependent on the substrate and reagent.

A new first-generation catalyst system for nucleophilic catalysis is developed. It is based on a planar chiral ferrocene skeleton with either the potent nucleophile 4-(dimethylamino)pyridine (DMAP) or the related 4-nitropyridine N-oxide attached in either the 2- or the 3-position.

A kinetic study for the nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzensulfonates [X=4-MeOm and X=4-No (sub 2)] with a series of primary amines in 80 mol % H2O /20 mol % DMSO at 25.0 degree Celsius is reported. The reactions proceed through S-O and C-O bond fission pathways competitively.

A diverse array of oxometallic species were examined as catalysts in nucleophilic acyl substitution (NAS) reactions of methyl (or ethyl) esters with protic nucleophiles. The new NAS protocol is also amenable to amines and thiols in 74-91% yields, albeit with higher loading (2.4 equiv) of protic nucleophiles.

The acylations of protic neucleophiles including alcohols, amines, and thiols are important and commonly used transformations in organic synthesis. The resultant esters, amides, and thioesters constitute three major classes of carboxylic acid derivatives, serving as important functional components and/or intermediates in synthetic chemistry and biological systems.

A new and efficient enantioselective synthesis of both enantiomers of syn-(3-trifluoromethyl)isoserine is achieved through a study. Ring opening of trifluoromethylated cyclic sulfates, derived from enantiopure trifluoromethylated vicinal diols, with various nucleophiles occurred exclusively at C2 with inversion of chirality.

The addition of various nucleophilic reagents to [ABC] subunits 2 and 7 possessing a pyrrolobenzazepine core is examined in connection with a total synthesis of cephalotaxine (1a). The result show that the nitrile end should be able to chemoselectivity complex a variety of Lewis acids, hence lowering the electron density in the enaminonitrile system.

The construction of novel derivatives has been made possible because of a nucleophilic substitution at a methylene attached to the bridgehead (1-) position of the 2-azabicyclo[2.1.1]hexane ring system. This provides access to epibatidine analogues, which contains heterocyclic substituents, and to homologation at the 1-position.

Direct electrophilic trifluoromethylation has been scarcely studied and few reagents have been developed for this use. For a long time, bioactive trifluoromethylated compounds have been prepared from trifluoromethylated 'building blocks' through iterative modifications.

Inversion of secondary alcohols by the SN2 reaction of a cesium carboxylate with a secondary sulfonate in DMF is widely used in synthesis. A synthesis of DMAP catalyzing the displacement of secondary sulfonates by cesium carboxylates in toluene at reflux providing alternative to 18-crown-6 is discussed.