General Mechanistic Considerations

Asymmetric Organocatalysts. Albrecht Berkessel and Harald Groger Copyright 2005 WILEY-VCH Veriag GmbH Co. KGaA, Weinheim ISBN 3-527-30517-3 

In many instances non-covalent catalysis relies on the formation of hydrogen- 

Specific mechanistic information on the organocatalytic processes discussed in this book is given in the individual chapters. 

Chemical Approach to Enzyme Action, 3rd edn, Springer, New York, 1991. 

Williams, Organic and Bio-Organic Mechanisms, Longman, Harlow, 1997. 

Of these approaches, (a) clearly is the one that is closest to the heart of the organic chemist, used to write down curved arrow mechanisms involving the minimum number of species and transition states compatible with experimental facts at a moment s notice. However, before this approach is attempted, it is appropriate to analyze what one actually is trying to do in applying concepts from homogeneous solution chemistry to electrode processes. The overridingly important question is Is it at all possible  

For a complete understanding of the chemical mechanism of an organic electrode process the following questions have to be satisfactorily answered  

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Another attempt to perform a general mechanistic consideration of [3 + 21-cycloaddition reactions of nitronates with olefins has been made relatively recently by Prof. Denmark and coworkers (162) using modern quantum-chemical methods, which allow one to correctly calculate the potential energy surfaces for model substrates. Since these data have been summarized in the recent review (335), it is not necessary to consider them as comprehensively as the study in (337). 

Orientation of addition is in accordance with general mechanistic considerations for 1,3-dipolar cycloadditions, and is highly regioselec-tive.27,34,40,171-174 The addition of p-nitrophenyl azide to styrene, however, is an exception the triazoline (21) and an aziridine obtained from thermolysis of the isomeric triazoline (20) are the products (Scheme 27).110,175... 

General Mechanistic Considerations From Solution and Gas-Phase Studies... 

Scheme 7.1 General mechanistic considerations for radical additions to C—C bonds.

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