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Study presents results that correct unambiguously the wrong stereochemical structure attribution of ethyl Z- alpha,alpha-difluoro 4-phenyl-3-butenoate resulting from the addition of the ethyl difluoroacetate radical to phenylacetylene. A novel and efficient method for the stereoselective preparation of pure ethyl E-alpha,alpha-difluoro-4-phenyl-3-butenoate is developed.

Ring-opening/ring-closing metathesis on cyclobutene-containing substrates with angular oxygen functionality provides a stereospecific introduction of 1,5-bis-dienes required for an anion-accelerated oxy-Cope rearrangement. The reaction sequence offers generally a stereocontrolled preparation of a variety of medium ring-containing bicyclic ring systems.

The allowed-forbidden gap of cyclobutene ring-opening is dependent on the planarity of the ring-opening transition structure. Skeletal structures that prevent the transition state from achieving the cyclic delocalization that is intrinsic to pericyclic transition states would reduce, or even eliminate, the energy of concert of a pericyclic reaction.

The structure of trans-3,4-difluorocyclobutene (tDCFB) is studied via microwave spectra. Rotational constants for isotopomers of tDFCB are obtained from microwave spectroscopy.

The far-infrared spectrum of gaseous 3-fluoro-1-butene, CH2=CHC(CH3)FH, was recorded at a resolution of 0.10 cm(super -1). The asymmetric torsional fundamentals of the most stable form HE and the higher energy FE conformations were observed at 88.7 and 105.9 cm(super -1) respectively.

The application of cyclobutenone complex as a dienophile in the various Diels-Alder cycloaddition reactions is analyzed. These compounds are shown to be much more reactive and beneficial than other compounds.

The kinetics of the B[F.sub.3]-catalyzed ring-opening reaction of various endo/exo m- and p-substituted diarylhomobenzoquinone epoxides are examined in CD[Cl.sub.3] in order to elucidate the remote [pi]-aryl participation. The studies have shown that the geometrical characteristics of the vacant oxirane Walsh orbital and the cyclobutene antibonding orbital has played a vital role in the topological features of [[eta].sup.2] [pi]-aryl participation.

The application of supercritical carbon dioxide as an environmentally friendly alternative to conventional organic solvents for the synthesis of a variety of carboxylic amides is described. Preliminary experiments with an objective to develop an intramolecular variant of amide synthesis which afford macrolactams indicated that the application of C[O.sub.2]/co-solvent mixtures might offer advantages for the synthesis of large-ring compounds.

An asymmetric synthesis of the potent substance P receptor antagonist (+)-CP-99,994 from 4-phenyl-1-butene is described. The synthesis involved Pd(0)-catalyzed asymmetric allylic and homoallylic C-H diamination.

A two-step procedure is described for preparing 2-alkyl-1,3-butadienes. Cuprate addition to 1,4-dibromo-2-butene has produced 3-alkyl-4-bromo-1-butene, a product of [S.sub.N]2 substitution and dehydrohalogenation has produced 2-alkyl-1,3-butadienes.

The first productive reactions of a metallacyclobutene complex with alkenes to yield 1,4-diene complexes with excellent regio- and stereochemical control are reported. The results provide insight into the reaction mechanism that involves conversion of the metallacyclobutene to a vinylcarbene intermediate which then undergoes a [4+2]-cycloaddition reaction with the activated alkene.

The electron momentum spectroscopy (EMS) technique is employed to study the conformational stability and valence-shell electron momentum distributions for 1-butene. The skew conformer of the complex is shown to be more stable than the syn conformer in the gas-phase.

High-resolution electron energy loss spectroscopy, temperature-programmed desorption and density functional theory calculations are used for studying the adsorption and reaction of 1-epoxy-3-butene (EpB) on Pt(111). The results have described the selectivity trends for reactions of EpB on Pt catalysts and bimetallic PtAg catalysts, indicating that the enhanced olefin hydrogenation selectivity of PtAg catalysts might originate from a bifunctional effect.

Variable temperature studies of the infrared spectra of 4-fluoro-1-butene, C[H.sub.2]=CHC[H.sub.2]C[H.sub.2]F, dissolved in liquid krypton is reported. The finding from the study provides insight into the structural parameters, dipole moments, conformational stability, vibrational frequencies, infrared, and Raman intensities.

The reactivity of disilyne RSi=SiR (R=Si'Pr[[[CH[(Si[Me.sub.3]).sub.2].sub.2]) toward [pi]-bonds is studied. The reaction takes place due to a stereospecific addition and hence opens up a new route for the synthesis of an isolable 1,2-disilabenzene compound.

A mild and general CO gas-free procedure is described for the synthesis of fused [alpha],[beta]-butenolides by the hetero-Pauson-Khand reaction (PKR) of alkynyl aldehydes. The exposure of the enantiomerically pure aldehyde to the usual Mo-mediated reaction conditions afforded the butenolide with complete exo selectivity.

A study describes a facile and mild transformation of benzocyclobutenones to 2,3-benzodiazepines, which is a biologically important heterocyclic core structure. The transformation is accomplished through a diazomethylene anion followed by a cascade electrocyclic reaction sequence involving a formal and net diazomethylene insertion into the cyclobutene ring.

The unrestricted second-order Moller-Plesset perturbation and complete basis set CBS-4M level methods is used to investigate the reaction of O[sup.3.P] with isobutene {{[CH.sub.3]}[.sub.2)]C=[CH.sub.2]}. The experimental results show that site selectivity of the addition of O[sup.3.P] to the terminal carbon atom of double bond of isobutene is weak.

The diverse array of rearrangement reactions catalyzed by PtCl2 is explained as a result of evidence provided for an essential component of the cationic manifold. The findings indicate that access is gained to various target structures of significant complexity from readily available starting materials.

The isolation and structural determination of 3,4-diphosphacyclobutenes is reported. The reduction with sodium naphthalenide to give the corresponding ring-opened products through P-P bond cleavage is described.

The reaction of lithium alkyneselenolate with alpha,beta-unsaturated ketone and then alkyl or acyl halide afforded 3-acyl-1-alkyl-2-alkylseleno-1-cyclobutene. Alkylselenocyclobutene and alkylthiocyclobutene were important molecules as a precursor for the preparation of cyclobutenone.

Step polymerization chemistry is used to complete a structural investigation of precise ethylene/1-butene (EB) copolymers. Acyclic diene metathesis polymerization has proven to control the primary structure of ethylene

The molecular structure of octafluorobicyclo[2.2.0]hex-1(4)-ene is measured in the gas phase by electron diffraction at room-temperature. The bond-altering effects of electrostatic repulsions and rehybridization arise from electronegativity differences.