Dienes In The Diels Alder Reaction

70 Jahre Forschung an der Diels-Alder-Reaktion: Dieses Buch fasst die wichtigsten und beeindruckendsten Ergebnisse in einzigartiger Weise zusammen! Zunächst werden die Grundprinzipien der Reaktion klar und verständlich anhand übersichtlicher Graphiken erläutert. Spezielle Vorschriften und gegebenenfalls ihre industrielle Umsetzung werden anschließend erklärt. Einen Schwerpunkt bilden auch physikalische und katalytische Verfahren zur Steigerung der Selektivität der Reaktion. Cycloadditionen in konventionellen und unkonventionellen Medien werden vorgestellt. Mit über 1.000 Literaturverweisen!

Dealing with the intermolecular Diels-Alder reaction, this book focuses on one of the reactants - the diene. Following an examination of the fundamental principles of the reaction are descriptions of the salient features of the different classes of dienes.

The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain—or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book opens with a review of the elementary aspects of the molecular orbital theory of bonding. This is followed by separate chapters on correlation diagrams, the conservation of orbital symmetry, theory of electrocyclic reactions, theory of cycloadditions and cycloreversions, and theory of sigmatropic reactions. Subsequent chapters deal with group transfers and eliminations; secondary conformational effects in concerted cycloaddition reactions; and generalized selection rules for pericyclic reactions.

The Diels-Alder reaction has long been a powerful tool in organic synthesis. In recent years, the Alder ene reaction has also achieved some prominence. From the beginning, it was apparent that the intramolecular variants of these reactions would be feasible. Many such have been reported, but the results are widely scattered in the chemical literature. This volume is an attempt to synthesize results observed to date, and to suggest directions for future development. One of the limiting factors in the application of the intramolecular Diels Alder reaction has been the development of methods for the preparation of the requisite trienes. The fIrst chapter of this volume summarizes methods for the preparation of dienes and dienophiles. Examples representative of every general approach to 1,3-dienes and to dienophilic functional group combinations have been included. There are two questions one might ask in considering the prospective cyclization of a given triene: what are the factors that govern the rate of cyclization? and, for cyclizations that lead to the creation of one or more new chiral centers, what are the factors that govern diastereoselectivity? These questions are addressed in Chapter Two. The third chapter is devoted to the all-carbon intramolecular Alder ene reaction. The tables in that chapter summarize all examples that could be found in the literature through 1981, with several additional examples from 1982. Leading references to heterocyclic ene reactions are also included in this chapter.

Organic Chemistry: A Series of Monographs, Volume 47: Hetero Diels-Alder Methodology in Organic Synthesis focuses on the use of hetero Diels-Alder reactions as pivotal steps in natural product total syntheses. The publication first offers information on N-sulfinyl compounds and sulfur diimides and imino dienophiles. Discussions focus on sulfur dioxide and related compounds, selenium dioxide, sulfur diimide cycloadditions, regiochemical, stereochemical, and mechanistic aspects, iminium salts and neutral imines, oximino compounds, and intramolecular cycloadditions. The text then takes a look at nitroso and thionitroso dienophiles and carbonyl dienophiles. The manuscript elaborates on thiocarbonyl and selenocarbonyl dienophiles and miscellaneous dienophiles. Topics include nitriles, azo compounds, selenoaldehydes, thioketones, thioesters, dithioesters, and related compounds, and thiophosgene and related compounds. The text also ponders on oxabutadienes, thiabutadienes, and azabutadienes. The publication is a valuable reference for chemists and readers interested in the Hetero Diels-Alder methodology.

Mechanochemical Organic Synthesis is a comprehensive reference that not only synthesizes the current literature but also offers practical protocols that industrial and academic scientists can immediately put to use in their daily work. Increasing interest in green chemistry has led to the development of numerous environmentally-friendly methodologies for the synthesis of organic molecules of interest. Amongst the green methodologies drawing attention, mechanochemistry is emerging as a promising method to circumvent the use of toxic solvents and reagents as well as to increase energy efficiency. The development of synthetic strategies that require less, or the minimal, amount of energy to carry out a specific reaction with optimum productivity is of vital importance for large-scale industrial production. Experimental procedures at room temperature are the mildest reaction conditions (essentially required for many temperature-sensitive organic substrates as a key step in multi-step sequence reactions) and are the core of mechanochemical organic synthesis. This green synthetic method is now emerging in a very progressive manner and until now, there is no book that reviews the recent developments in this area. Features cutting-edge research in the field of mechanochemical organic synthesis for more sustainable reactions Integrates advances in green chemistry research into industrial applications and process development Focuses on designing techniques in organic synthesis directed toward mild reaction conditions Includes global coverage of mechanochemical synthetic protocols for the generation of organic compounds

Organic Chemistry is a proven teaching tool that makes contemporary organic chemistry accessible, introducing cutting-edge research in a fresh and student-friendly way. Its authors are both accomplished researchers and educators.

Since the discovery of the Diels-Alder reaction in 1928, chemical theorists have pursued a deeper understanding of the factors controlling reactivity and stereoselectivity for this reaction. Cyclopentadiene and cyclopropene are unusual, in that they exhibit rapid Diels-Alder reactivity despite their lack of activating electron withdrawing or donating groups. The rapid reactivities of cyclopentadienes result from the minimal distortion required of cyclopentadiene to achieve the envelope-like geometry adopted in the transition state, while the rapid reactivities of cyclopropenes result from reactant distortion and the highly stabilizing orbital interactions present at the transition state. Substituents at the 3-position of cyclopropenes and the 5-position of cyclopentadienes significantly influence the Diels-Alder reactivity through hyperconjugative interactions of the substituent with the cyclic -system. Hyperconjugative acceptors stabilize cyclopropenes and decrease the reactivity by invoking aromatic cyclic delocalization of the two -electrons and the reactivity decreases. The effect is opposite for cyclopentadienes, where hyperconjugative acceptors induce antiaromatic cyclic delocalization of the four -electrons, destabilizing the diene and promoting reactivity. The syn and anti -facial selectivity of 5-substituted cyclopentadienes is related to the electronic nature of the substituent. Experimentally, electron-withdrawing groups provide syn adducts, while electron-donating groups provide anti adducts. Structural analysis of the ground state geometries revealed that -acceptors pre-distort the cyclopentadiene into an envelope-like geometry that minimizes the destabilizing effect of the negative hyperconjugation. This envelope geometry resembles the syn transition state geometry and promotes syn selectivity by minimizing the distortion energy required to achieve the syn transition state. Conversely, donors pre-distort in the opposite direction to maximize the stabilizing effect the hyperconjugative interaction towards an envelope geometry that favors the anti cycloaddition. The computational insights into the reactivities of cyclopentadienes inspired us to develop cyclopentadiene as a bioorthogonal reagent. Bioorthogonal reactions take place rapidly and selectively in biological environments and enable the study of biomolecules in living systems. Highly accurate computational methods were used to screen potential bioorthogonal cyclopentadiene candidates. The screening revealed tetrachlorocyclopentadiene ketals as highly reactive and stable dienes with promising bioorthogonal potential. To verify our prediction, the Murphy group bioconjugated a tetrachlorocyclopentadiene ketal it to a peptide and labeled the peptide with trans-cyclooctene dye. Some cyclopentadienes are now considered viable bioorthogonal reagents.