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The transient spectroscopic studies of the photocyclopropanation reaction between the C[H.sub.2]I-I isomer of C[H.sub.2][I.sub.2] and several cycloalkenes is reported. The cycloalkene ring size is found to have a modest effect on the reaction rate, while methyl substitution of the cyclohexene C=C bond has a more pronounced effect.

The viability of alkene metathesis in platinum coordination spheres is established along with other reactions for the construction of novel sterically shielding polyynediyl complexes. The results have shown that complexes with termini-spanning diphosphines show [sp.sup.3] chains with both double-helical and non-helical conformations and highly shielded sp chains.

The study presents a mechanistic research and investigation of intramolecular aminoalkene and aminoalkyne hydroamination/cyclization that is normally catalyzed by several highly electrophilic and tetravalent constrained geometry complexes. The existence of identical reactivity trends, rate laws and activation parameters of the complexes prove the formation of an M-N [sigma]-bonded insertive pathway in the substance.

Exo-triazolines are prepared by adding azides to acylnitroso hetero-Diels-Alder cycloadducts that are derived from cyclopentadiene. The steric bulk of the azide has no significant role in the course of reaction, but the reactivity of the alkene is diminished significantly in cycloadducts derived from larger cyclic dienes or in monocyclic alkenes.

The reaction class transition state theory (RC-TST) combined with the linear energy relationship (LER) and the barrier height grouping (BHG) approach was used to study the kinetics of the hydrogen abstraction reaction class of the H + alkene. The analysis has indicated that less than 50% systematic errors on the average are present in the predicted rate constants using the RC-TST/LER or RC-TST/BHG method while in comparison to explicit rate calculations the differences are less than 100% or a factor of 2 on the average.

Diels-Alder reactions of 4-alkenylthiazoles were carried out to find a new approach to thaizole functionalization. Diels-Alder reactions included reactions of N-substituted maleimides, maleic anhydride and napthoquinone with high levels of stereocontrol to give the corresponding endo-cycloadducts.

A wide range of palladium-catalyzed processes involving oxidation addition/reductive elimination chemistry, which were developed to prepare heterocycles with the emphasis on fundamental processes used to generate the ring systems themselves, is reviewed. This chemistry generally involves initial oxidative addition of an organic halide or triflate to the palladium(0) complex, which readily undergoes intramolecular nucleophilic attack by a neighboring nucleophile, or addition to an alkene, alkyne, or carbon monoxide.

A series of bimetallic organo-group 4 'constrained geometry' catalysts and binuclear bisborane and bisborate cocatalysts have been synthesized to probe catalyst center--catalyst center cooperativity effects on olefin enchainment in homogenous olefin polymerization and copolymerization processes. Significant nuclearity effects are found versus mononuclear controls, and the effect can be correlated with metal-metal approach distances and ion pairing effects. Novel polymer structures can be obtained by using such binuclear catalyst/cocatalyst systems. catalysis | polymer | polyolefin

Novel alkene and alkyne branched structures are synthesized and their two-photon absorption (2PA) properties are investigated. The results have shown that alkene branched system have higher 2PA cross sections and that alkene and alkyne [pi]-extended systems with acceptors such as pyridine have better 2PA properties, which would serve as good building blocks for larger branched systems.

An attempt is made to study the nonchelated alkene complexes of the [d.sup.0]-metal species, to probe the [Zr.sup.IV]-alkene interaction. Alkene coordination is inhibited by sterically bulky substituents on the alkene but is greatly enhanced by electron-donating groups and the [beta]-Si effect.

Mass spectrometry has become an essential tool in delineating the structural properties of a new series of amino acid functionalized acyclic diene metathesis (ADMET) polymers known as bioolefins. These measurements, coupled with the measurement of the polymers chemical and physical properties, assist in the determination of their utility as biomaterials. In the present study, a set of five polymers with different bulk size and electronic properties were chosen for structural analyses by MALDI-TOF, MALDI-FTICR, and DIOS-TOF. The obtained data show that due to the competing metathesis and isomerization during ADMET, depending on their structural properties, the olefins display different selectivity toward main metathesis or isomerized products.

A quantitative structure-activity relationship (QSAR) model is described in which both the independent and dependent variables are derived from density functional theory (DFT) calculations on large 14-electron complexes. This strategy can be used for broader screenings of olefin metathesis catalysts as well as for development of homogeneous transition metal catalysts.

The evolution of a convergent strategy that led to efficient, enantioselective syntheses of both natural (+)- and unnatural (-)-guanacastepene E and formal total syntheses of (+)- and (-)-guanacastepene A is described. The convergent strategy has given rise to guanacastepene E in 28 steps with a longest linear sequence of 20 steps.

The novel molybdenum oxo-imido bis-(aryloxide) complexes are prepared by the salt elimination reactions of [Mo(N'Bu)(O)[CI.sub.2](DME)] with the lithium aryloxide of from the cycloaddition reactions of tert-butyl isocyanate with the appropriate molybdenum dioxo bis(aryloxide) complex. The geometry around the metal in complexes is described as a distorted trigonal bipyramid, with the imido and pyridine ligands occupying axial positions and the oxo and aryloxide ligands in the equatorial plane.

A stereocontrolled total synthesis of kendomycin (-)-1 was achieved, which proceeds with a longest linear sequence of 21 steps beginning with commercially available 2,4-dimethoxy-3-methylbenzaldehyde(12). Highlights of the synthesis include an effective Petasis-Ferrier union/rearrangement tactic to construct the sterically encumbered tetrahydropyran ring, a ring-closing metathesis to generate the C(4a-13-20a) macrocycle.

The selective transformation of allenylidene complexes ((n(super 6)-p-cymene)RuCl(=C=C=CAr2)(PR3))X (4) into alkene metathesis catalytic species is reported. The (arene)ruthenium-allenylidene complexes in situ rearrange, via alkenylcarbyne intermediates ((n(super 6)-p-cymene)RuCl(=CCH=CR2)(PR3))X2 into (arene)ruthenium indenylidene derivatives ((n(super 6)-arene)RuCl(ind)(PR3))X, in the presence of acid.

Three phenylpropene structural isomers were used to examine the correlation between adsorption geometry and oxidation geometry. The importance of adsorption geometry is demonstrated and it is confirmed that allylic H stripping is indeed a key process that limits epoxidation selectivity in such cases.

An alkene, orthogonene is computationally reinvestigated. The vertical ionization energy of the alkene molecule is predicted to be ca. 5.3 eV, comparable to that of the alkali metals and similar to that predicted by others for a hypothetical planar tetracoordinate carbon molecule.

A stereoselective strategy for the replacement of the 1,2-dihaloalkene bridge of tetrahalonorbornyl derivatives by an oxygen bridge involving stepwise controlled oxidation, cleavage of the dione thus formed, and reiterative intramolecular S(sub N)2 displacement of two bridgehead halogens is devised. The synthesis of four highly strained pentacyclic bis-oxa-bridged derivatives with interesting structural variations is presented.

The dependence of organic acid generation by alkene ozonolysis on relative humidity, thermalized Criegee intermediate scavengers, and alkene structure is investigated. The results indicate that stabilized Criegee intermediates (SCI) and their reaction with water are minor contributors to acid formation in the atmosphere and suggest that many of the acids are formed directly.

The syntheses and reactivities of sterically encumbered trans-dioxoosmium(VI) complexes containing Schiff-base ligands bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamine (H2(super t)Bu-salch) and bis(3,5-dibromosalicylidene)-1,2-cyclohexane-diamine (H2BR-salch) are described. Product formation is shown to occur more quickly for reactions derived from alkenes substituted with an electron-donating group compared to those derived from electron-withdrawing substituted alkenes.

A new class of bifunctional catalysts bearing a thiourea moiety and an amino group on a chiral scaffold was synthesized. Thiourea bearing 3,5-bis(trifluoromethyl)benzene and dimethylamino groups were revealed to be highly efficient for the asymmetric Michael reaction of 1,3-dicarbonyl compounds to nitroolefins.

The ability of a diverse set of chiral ligands to effect enantiofacially selective cyclization of 2-(N,N-diallylamino)phenyllithium is investigated. Although none of the ligands afforded 1-allyl-3-methylindoline in higher ee than previously observed for the cyclization of 2-(N,N-diallylamino)phenyllithium in the presence of the benchmark ligand (-)-sparteine, several ligands, structurally unrelated to sparteine and available in either enantiomeric form, were found to match the utility of (-)-sparteine in this chemistry

The analysis indicates that the origin of enantioselectivity in the ring-closing metathesis of achiral trienes is correlated to the chiral folding of the N-bonded aromatic groups, which is imposed by the Ph groups in positions 4 and 5 of the imidazole ring of the N-heterocyclic(NHC) ligand. The mechanism of enantioselectivity in the asymmectric Ru-catalyzed metathesis of olefins is investigated with a theoretical approdach.

C2-symmetric bis(oxazolinato)lanthanide complexes catalyze enantioselective intramolecular hydroamination/cyclization of aminoalkenes and aminodienes with good rates and enantioselectivities comparable to or greater than those obtained with difficult substrates. The rare example of enantioselective hydroamination catalyzed by nonmetallocene lanthanide complexes is presented.

The sulphur K-edge X-ray absorption near-edge structure (XANES) spectra of self-assembled monolayers for a series of n-alkanethiols adsorbed on Ag(111) is studied. The effects of chain length and incidence angle on the XANES spectra are investigated.

A series of para-substituted triaryl phosphine-based ruthenium olefin metathesis catalysts are synthesized and studied. The catalyst initiation can be attenuated by tuning phosphine electronics since a linear free energy relationship exists between phosphine sigma-donor strength and the rate of catalyst initiation (phosphine dissociation).

A small library of H-pin polyamides with variable aliphatic bridge lengths ((CH2)(sub n)), where n=4-8, connecting a central Py/Py pair is prepared via parallel synthesis with Ru-catalyzed alkene metathesis on solid phase as a complexity-generating cross-linking reaction. DNA binding affinities and sequence specificities were analyzed for each member of the library to determine the optimum linker length.

The products and mechanism of secondary organic aerosol formation from reactions of O3 with cylcohexne, cycloheptene, cyclooctene and cyclodecene is investigated, in the presence of alcohols, using a thermal desorption particle beam mass spectrometer. The alkoxyhydroperoxy aldehydes appeared to undergo little intermolecular reaction to form dimers or polymeric peroxyhemiaacetals.

A study of the trimethylene cross-link in a GpC motif using the reverse sequence is made. In the CpG sequence the cross-link assumed an almost planar conformation while the GpC cross-link adopted a helical conformation and destabilized the duplex.

Protected analogues of nucleosides 3'-phosphates, in which the esterified oxygen atom is replaced by a difluoromethylene unit, have been prepared for the first time and the addition of the lithium salt of difluoromethylphosphonothioate was key step to the synthesis. The beneficial presence of the sulfur atom in this reagent translates into greatly increased yields, reproducibilities, and ease of purification.

Paths of Diels-Alder reactions of dienes and olefins with symmetric geometries are determined. Many reactions take the Cs-symmetry paths obeying the W-H rule, whereas those of strong nucleophilic dienes and electrophilic olefins do not follow the symmetry-conservation rule.

Alkoxyalkyl and haloalkyl radicals are added to the enoates with moderate to good diasteroselectivity. The result show that the additions of prochiral radicals to prochiral alkenes via open transition states is not uniformally highly diasteroselective.

A mechanism for the reaction of the NO3 radical with propene is proposed and discussed on the basis of B3LYP and CASSCF calculations. Comparison of the optimized geometries on a limited number of molecular structures was implemented with calculations at the CASSCF level of theory with the same basis set, building the active space with five electrons in six orbitals.

Several solid-state [91 sup]Zr NMR spectroscopy studies are conducted to explain the formation, structure and properties of the zirconocene olefin polymerization catalyst precursors. The approach is shown to be extremely beneficial for studying the molecular structure of various such catalysts.

The application of the iron(II) complexes of a series of N-acylated dipyridin-2-ylmethylamine ligands (R-DPAH) for the olefins cis-hydroxylation is explained. The complete processes involved in the [Fe.sup.II]/[Fe.sup.IV] catalytic cycle are also analyzed.

Several mechanistic studies are conducted to explain the mechanisms involved in the reactions taking place between the aromatic ketones with olefins. The rate of C-H/olefin coupling is shown to exhibit a complete dependence on the concentration of the ruthenium complex in the system.

The selective adsorption of ethane taking place over ethylene taking place in the mixtures on the zeolite imidazole framework ZIF-7 via a gate-opening mechanism is explained. The results demonstrate that ZIF-7 is an extremely important compound for the separation of olefins from paraffins.

The mechanisms involved in the mild mild palladium-mediated bisolefination of C- C triple bonds are explained. The observed bisolefination process is shown to be extremely beneficial for the production of different naphthalene derivatives.

The various mechanisms involved in the copper-catalyzed intermolecular oxidative [3 + 2] cycloaddition of alkenes with anhydrides via oxygen as a sole oxidant are discussed. The reaction is shown to be extremely beneficial for the synthesis of [gamma]-lactones.

Chemo- and diastereoselective olefinic oxidation of unsaturated amines in the presence of HB[F.sub.4] and BnOH is performed to prepare the enantiomers of 1-deoxynojirimycin and 1-deoxyaltronojirimycin. Ring contraction to (2S,3R,4S,5S,1'R)-N(1)-benzyl-2-chloromethyl-3-benzyloxy-4,5-epoxypiperidine followed by regioselective epoxide ring opening, functional group manipulation, and deprotection gave (+)-1-deoxyaltronojirimycin is utilized to elaborate the highly functionalized intermediate.

The reaction between a phosphonate diester anion and a P(III) chlorophosphine, or its P(V) borane complex were used to obtain mixed 1,1-bisphosphorus compounds. The reaction is found to be competitive with other methods for the synthesis of alkenyl phosphorus compounds and could be used to prepare a variety of a novel organophosphorus reagents and products.

The development of radical halo-nitration of alkenes using iron(III) nitrate nonahydrate and halogen salt and its application for the synthesis of nitroalkenes is described. The practical application of the developed method for the broader range of alkenes is demonstrated by using nontoxic and inexpensive iron reagents.

A two-step cyclization reaction followed by Fe[Cl.sub.3]-mediated intramolecular cyclodehydrogenation, was carried out on the olefin precursors to obtain a new family of contorted 1.2,3.4,7.8,9.10-tetrabenzocoronenes (TBCs). The newly obtained TBC molecules bear contorted conformation due to steric overcrowding and exhibited extended [pi]-conjugation compared with coronene and strong aggregation in solution.

The first, general and highly efficient catalyst system is developed that has allowed a wide range of activated and unactivated aryl chlorides to couple regioselectively with olefins. Ethylene glycol has played a double role in the arylation, which has facilitated oxidative addition and has promoted the subsequent dissociation of chloride from Pd(II) to produce a cationic Pd(II)-olefin species.

A strategy is described for designing high-performance, ambipolar, acene-based field-effect transistor (FET) materials, which is based on the replacement of C-H moieties by nitrogen atoms in oligoacenes. The demonstration of high and balanced ambipolar FET properties from nitrogen-containing oligoacenes has provided new opportunities for designing high-performance ambipolar organic semiconductors.

A Rh-catalyzed, regio- and enatioselective intermolecular olefin hydroacylation is described under mild conditions. Hydroacylations between homoallylic sulfides, containing a substrate-bound directing group, and salicylaldehyde derivatives have occurred in the presence of a spiro-phosphoramidite ligand, (R)-SIPHOS-PE, to produce [alpha]-branched ketones.

A chiral phosphine-catalyzed homodimerization of ketoketenes is developed to access variety of highly substituted ketoketene dimer [beta]-lactones. Ring-opening reactions of the enantioenriched ketoketene dimers to access 1,3-diketones, enol esters and [beta]-hydroxyketones with good diastereoselectivity is also reported.

Enantioselective cyclization of E- and Z-configured allylic bis-trichloroacetimidates to highly enantioenriched 2-trichloromethyl-4-vinyloxazoline in presence of cationic Pd(II) catalysts generated from chiral biphenyl diphosphine complexes or from COP-Cl is described. The process is an excellent example for olefin amination in high yield and enantioselectivity with trichloroacetimidate as the N-nucleophile to provide an easy-to-deprotect enantioenriched vinylglycinol derivative in presence of cationic palladium(II) complex.