5009-11-0

The infrared spectra (3500-50 cm-1) of the gas and solid and the Raman spectra (3500-50 cm-1) of the liquid and solid have been recorded for 1-hexen-4-yne, CH2=CHCH2C≡CCH3. Also variable temperature studies over the temperature range -105 to -150°C of the infrared spectra (3500-400 cm-1) of the sample dissolved in liquid krypton have been carried out. By utilizing these data from seven cis/gauche conformer pairs, the cis conformer is found to be the lower energy form with an enthalpy difference of 233 ± 23 cm-1 (2.79 ± 0.28 kJ mol-1). At room temperature it is estimated that there is 39 ± 2% of the gauche conformer present. Equilibrium geometries and energies of the two conformers have been predicted from ab initio calculations by perturbation theory (MP2) with full electron correlation to second order and hybrid density functional theory (DFT) calculations by the B3LYP method with a number of basis sets. A complete vibrational assignment is proposed for the cis conformer based on the vibrational-rotational band contours, relative intensities, Raman depolarization ratios and predicted frequencies from the ab initio and DFT calculations and many of the fundamentals for the gauche form have been assigned. The observation of sub-band structure for two of the nearly degenerate methyl vibrations indicates that the CH3 group has almost free internal rotation which is consistent with the ab initio predicted barrier of 100 cm-1. From the spacings of the sub-bands the values of the Coriolis coupling constants, ζ, have been determined for the CH3 stretch and deformation.

Methods for preparation of olefins, including 8- and 11-unsaturated monoenes and polyenes, via transition metathesis-based synthetic routes are described. Metathesis reactions in the methods are catalyzed by transition metal catalysts including tungsten-, molybdenum-, and ruthenium-based catalysts. The olefins include insect pheromones useful in a number of agricultural applications.

-

Five Diels-Alder adducts of anthracene, containing respectively the spiro cyclopropane (3), vinylcyclopropane (4), allenylcyclopropane (5) and methylenecyclopropane systems (6 and 7) have been synthesized and their flash thermolytic behaviour investigated.Whereas the adduct 3 undergoes exclusively a retro-Diels-Alder cleavage leading to methylenecyclopropane, two types of rearrangements are observed, owing to their structure, as predominant reaction paths with compound 4-7 : the adducts 4 and 5, possessing a vinylcyclopropane unit, almost only rearrange into the corresponding cyclopentene 14 and methylenecyclopentene 15, respectively; on the other hand, the methylenecyclopropene adducts 6 and 7 undergo a more unexpected rearrangement of the anthracenic framework leading to the polycyclic methylenecyclobutanes 19 and 20.The structure proposed for 19 follows unambiguously from its spectral properties and is confirmed by its ozonolysis yielding the cyclobutanone 21.In the same way, the retro-Diels-Alder cleavage of the adducts 4-7, also observed as a minor reaction path (10-40percent), is followed by the isomerization of the firstly obtained cyclopropanic cumulenes, leading to 1,4-hexadiyne (from 5), dimethylenecyclopropane (from 6), or 1-hexen-4-yne and ethylidenemethylenecyclopropane (from 7).