The cleavage and addition of ortho C−H bonds in various aromatic compounds such as ketones, esters, imines, imidates, nitrile, and aldehydes to olefins and acetlylenes can be achieved catalytically with the aid of ruthenium catalysts. The reaction is generally highly efficient and useful in synthetic methods. The coordination to the metal center by a heteroatom in directing groups such as carbonyl and imino groups is the key. The reductive elimination to form a C−C bond is the rate-determining step.

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Catalytic C−H/Olefin Coupling

Rotations and inversions in organic molecules are readily recognizable from the temperature dependence of the NMR spectra. The study of the effects of substituents on the activation barriers of such processes permits the elucidation of reaction mechanisms, and the stability limits of isomers can also be determined. The knowledge of the stability limits is necessary for the specific synthesis of stable rotamers and invertomers.

Detection of Hindered Rotation and Inversion by NMR Spectroscopy

Rotations- und Inversionsprozesse in organischen Molekulen geben sich durch die Temperaturabhangigkeit der NMR-Spektren zu erkennen. Das Studium der Substituenteneffekte auf die Aktivierungsbarrieren solcher Prozesse gestattet die Aufklarung von Reaktionsmechanismen, ferner lassen sich die Stabilitatsgrenzen von Isomeren ermitteln. Die Kenntnis der Stabilitatsgrenzen ist notwendig, um gezielt stabile Rotamere und Invertomere synthetisieren zu konnen.

Nachweis gehinderter Rotationen und Inversionen durch NMR‐Spektroskopie

The absorption spectrum of the uranyl ion in perchlorate media: Part I. Mathematical resolution of the Overlapping band structure and studies of the environmental effects

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Replacement of a cyclometalated terdentate diamino ligand by a phosphorus analogue. Isolation and crystallographic characterization of an intermediate in aryl C-H bond activation in models of dendrimer-bound organometallic catalysts

Geminal Proton Nonequivalences and Related Phenomena in Some N-Substituted Amides1

Studies of Adducts of Metal Salts with Tetraalkyl Alkyldiphosphonates. I. Proton Magnetic Resonance Spectra of Uranyl Nitrate Adducts of Methylenediphosphonates in CDCl3

Conformation of Organophosphorus Compounds. II. Proton Magnetic Resonance Studies of Some Phosphites, Phosphonites, Phosphates, Phosphonates and Additional Phosphinates

Conformation of Organophosphorus Compounds. I. Proton Magnetic Resonance Studies of Some Phosphinates, Phosphinic Acids, Phosphinyl Chlorides and Phosphonyl Dichlorides

IT has long been considered that nuclear magnetic resonance (NMR) should be a suitable technique for the demonstration of slow inversion in trivalent nitrogen compounds. However, only in the case of cyclic imines, such as N-ethylethyleneimine, has it been possible to demonstrate slow inversion by NMR1. Recently, Saunders and Yamata2 searched for evidence of slow inversion in dibenzyl methylamine, but found no evidence for non-equivalence of methylene protons in the amine itself. They were successful, however, in observing non-equivalence in the amine hydrochloride.

C. A. Prohaska

Papers

Geminal Proton Nonequivalences and Related Phenomena in Some N-Substituted Amides1

Studies of Adducts of Metal Salts with Tetraalkyl Alkyldiphosphonates. I. Proton Magnetic Resonance Spectra of Uranyl Nitrate Adducts of Methylenediphosphonates in CDCl3

Conformation of Organophosphorus Compounds. II. Proton Magnetic Resonance Studies of Some Phosphites, Phosphonites, Phosphates, Phosphonates and Additional Phosphinates

Conformation of Organophosphorus Compounds. I. Proton Magnetic Resonance Studies of Some Phosphinates, Phosphinic Acids, Phosphinyl Chlorides and Phosphonyl Dichlorides

Slow Inversion at the Nitrogen Atom in Certain Amides