Advances in Strained and Interesting Organic MoleculesThe eighth volume of this series comprises six chapters and describes a variety of interesting strained and not so strained molecules and their use - or abuse - in the widest sense. This volume contains a position summary of planar carbon networks, the field of strained allenesis addressed by considering the five- to- nine-membered ring derivatives and this is followed by an introduction to the nature of carbene geometry and the use of ESR spectroscopy in deducing carbene structure. The use of strained molecules in the synthesis of important new compounds of a natural and non-natural nature is a main theme in the volume. Other areas that are discussed are strained carbohydrates, stereocontrolled access to natural products and polymer systems as well as a much sought after contribution to the series on small-ring nitrogen heterocycles. |
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Page xi
... ROMP reaction. In this way amino acid, amino ester, peptide, and nucleic-acid base-containing polymers have been generated in living processes. In comparison, ozonolysis of enantiomerically pure norbornene-derived amido acids has ...
... ROMP reaction. In this way amino acid, amino ester, peptide, and nucleic-acid base-containing polymers have been generated in living processes. In comparison, ozonolysis of enantiomerically pure norbornene-derived amido acids has ...
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Contents
| 43 | |
CHAPTER 3 STRAIN AND STRUCTURE OF STERICALLY CONGESTED TRIPLET CARBENES | 83 |
OXABICYCLO41 0HEPTANES | 113 |
CHAPTER 5 EXPLOITING THE STRAIN IN 221 BICYCLIC SYSTEMS IN POLYMER AND SYNTHETIC ORGANIC CHEMISTRY | 145 |
CHAPTER 6 AZlRlNES AND AZlRlDlNES REVISITED | 187 |
INDEX | 259 |
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Advances in Strained and Interesting Organic Molecules, Volume 8 B. Halton No preview available - 2000 |
Common terms and phrases
2H-azirines aldehyde alkene alkylidene alkyne allyl Angew anhydride aromatic azide aziridines azirine Balci benzene bond angle carbene carbene center carbohydrates carbon atom catalyst Chem chemistry chiral complex compounds cyclic allenes cyclization cycloaddition cyclopentane cyclopropane Danishefsky delocalization derivatives diastereomer diastereoselectivity Diels–Alder dimerization Diphenylcarbenes double bond DPIBF electrons energy Engl epoxide ester Et3N formation formed geometry glycal graphyne hemiacetals heterocycles imines initiator intermediate intramolecular isomer isomeric kcal/mol lactone Lewis acid linear macrocycle matrix metathesis methyl groups mixture molecular molecule monomers nitrile nitrile ylide nitrogen norbornene nucleophilic observed olefin optically active orbital oxidation Ph Ph phenyl photolysis polymerization polymers potassium tert-butoxide prepared react reaction reactivity Reagents rearrangement regioselectivity reported ring expansion ring opening ring system ROMP Scheme 18 shown in Scheme SiMe3 stable steric strained structure substituents synthesis synthetic temperature Tetrahedron Lett Tomioka triplet carbenes undergo yield ZFS parameters
Popular passages
Page vii - School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand C Uher (A2.4) Department of Physics.
Page 85 - A£s) is roughly equal to the electron- electron repulsion minus the energy required to promote an electron from the a- to the p-nonbonding orbital. In other words, as the energy separation between a and p states increases, the promotion energy becomes large enough to overcome the repulsion energy, while if the spacing is small, the species will still have a triplet ground state.
Page 85 - ... p-nonbonding orbital. In other words, as the energy separation between a and p states increases, the promotion energy becomes large enough to overcome the repulsion energy, while if the spacing is small, the species will still have a triplet ground state. The small difference between the energies of S0 and TI may easily be overturned by the effects of substituents on the carbene center.
Page 253 - Lefemine, DV, Dann, M., Barbatschi, F., Hausmann, WK, Zbinovsky, V., Monnikendam, P., Adam, J., and Bohonos, N.
Page 85 - On the other hand, theory also suggests that opening of the central angle strongly destabilizes the singlet state, but requires very little additional energy for the triplet, thus making AGST larger [11].
Page 85 - As the carbenecarbon bond angle is contracted, the a orbital gains s character and consequently moves even lower in energy. The smaller the bond angle, the more energy it takes to promote an electron from the a to the p orbital, and the smaller A£ST becomes.
Page 89 - D implies a large spin-spin interaction and a close proximity of the two spins. The parameter E, on the other hand, is a measure of the difference between similar magnetic dipole interactions along the x and y axes. A...
Page 87 - Since there are three magnetic axes, and two transitions for each of the canonical orientations, one expects 3x2 = 6 lines for a triplet spectrum. The lines appear in pairs, according to whether they arise from structures which have the x, y or z principal magnetic axis nearly aligned with the external field.
Page 94 - C2v group. Therefore, bent molecules could be singlet states. However, it is not at all obvious that the energy minimum of the triplet state would inevitably have the linear configuration, although such has sometimes been assumed to be the case. Because bending would be accompanied by rehybridization, the relative amounts of s and...
Page 90 - Triplet polynuclear aromatic carbenes Introduction of aryl groups on methylene results in a significant decrease in D values; thus D decreases from 0.69 to 0.515 on going from methylene to phenylcarbene.