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Fakultät für Chemie und Pharmazie - Digitale Hochschulschriften der LMU - Teil 04/06 Podcast
Quantification of the electrophilic reactivities of nitroalkenes

Quantification of the electrophilic reactivities of nitroalkenes

Fakultät für Chemie und Pharmazie - Digitale Hochschulschriften der LMU - Teil 04/06 vor 14 Jahren

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While a large variety of nucleophiles (N and sN) have been
characterized according to eq 1.3, the number of E parameters for
electrophiles, and specifically for different classes of Michael
acceptors remains relatively small. A goal of this work was to
include the synthetically important trans--nitrostyrenes (Chapter
2) and aliphatic nitroolefins (Chapter 3) into our reactivity
scale, by measuring the rates of their reactions with stabilized
carbanions. The reactions of (E)-1-ethoxy-2-nitroethene with
pyridinium ylides, and of (E)-N,N-dimethyl-2-nitroethenamine with
stabilized carbanions will be discussed in Chapter 4. Considerable
effort has been spent on the development of organocatalytic
asymmetric Michael additions. The reactions of nitrostyrenes with
ketones or aldehydes have been used as model reactions for probing
the efficiency and selectivity of new organocatalysts. The kinetic
of the reaction of trans--nitrostyrene with cyclohexanone
catalyzed by pyrrolidine and benzoic acid has been investigated,
and the individual rate orders have been determined in order to
provide insight into the catalytic cycle (Chapter 5). Diazo
compounds are common and versatile reagents in organic synthesis
despite their hazardous nature. Therefore, the rates of reactions
of diazo compounds with Michael acceptors (Chapter 6) have been
studied in order to elucidate the degree of concertedness of these
1,3-dipolar cycloadditions, and to investigate if they can be
described by eq 1.3.