Cycloaddition chemistry

Grashey, R In 7 5 Dipolar Cycloaddition Chemistry, Padwa, A, Ed, Wiley New York, 1984, p 733 and literature cited therein... 

Cycloaddition reactions also have important applications for acyclic chalcogen-nitrogen species. Extensive studies have been carried out on the cycloaddition chemistry of [NSa]" which, unlike [NOa]", undergoes quantitative, cycloaddition reactions with unsaturated molecules such as alkenes, alkynes and nitriles (Section 5.3.2). ° The frontier orbital interactions involved in the cycloaddition of [NSa]" and alkynes are illustrated in Fig. 4.13. The HOMO ( Tn) and LUMO ( r ) of the sulfur-nitrogen species are of the correct symmetry to interact with the LUMO (tt ) and HOMO (tt) of a typical alkyne, respectively. Although both... 

A synthetically powerful method, an approach based on cycloaddition chemistry, allows one to assemble the pyridine ring in one step. Not only is this method efficient, atom economy, but also its convergency allows for the preparation for highly substituted systems in which one can, in principle, control all five positions on the pyridine ring. A versatile example of this methodology is the Boger reaction. It has been applied to the synthesis of a very diverse set of targets. 

Flamers R. J., Coulter S. K., Ellison M. D., Flovis J. S., Padowitz D. F., Schwartz M. P., Greenlief C. M., Russell J. N. Jr Cycloaddition Chemistry of Organic Molecules With Semiconductor Surfaces Acc. Chem. Res. 2000 33 617 624 Keywords carbonyi group, semiconductor materiais, surface reaction, aikenes, aromatic compounds, azo compounds, cycioaikadienes, isothiocyanates, unsaturated compounds... 

Padwa A. Application of Diels-Alder Cycloaddition Chemistry for Heterocyclic Synthesis Prog. Heterocycl. Chem. 1995 7 21-42... 

PadwaA(ed) (1984) 1,3-Dipolar cycloaddition chemistry. Wiley, New York... 

For comprehensive reviews of 1,3-dipolar cycloaddition reactions, see R. Huisgen, R. Grashey and J. Sauer in The Chemistry of Alkenes, S. Patai, ed., Interscience London, 1965, pp. 806-878 G. Bianchi, C. DeMicheli, and R. Gandolfi, in The Chemistry of Double Bonded Functional Groups, Part I, Supplement A, S. Patai, ed., Wiley-Interscience, New York, 1977, pp. 369-532 A. Padwa, ed., 1,3-Dipolar Cycloaddition Chemistry, Wiley, New York, 1984. 

As mentioned in the introduction, the prototype o-QM is a highly reactive intermediates in organic reactions, including cycloaddition chemistry and DNA covalent modification, due to the high electrophilicity at the exocylic methylene carbon (see its dipolar representation in Scheme 2.11). 

Advances in Cycloaddition Chemistry, ed. by D. P. Curran, JAI Press Inc. Greenwich, Connecticut,... 

Nitro compounds have been converted into various cyclic compounds via cycloaddition reactions. In particular, nitroalkenes have proved to be useful in Diels-Alder reactions. Under thermal conditions, they behave as electron-deficient alkenes and react with dienes to yield 3-nitrocy-clohexenes. Nitroalkenes can also act as heterodienes and react with olefins in the presence of Lewis acids to yield cyclic alkyl nitronates, which undergo [3+2] cycloaddition. Nitro compounds are precursors for nitrile oxides, alkyl nitronates, and trialkylsilyl nitronates, which undergo [3+2]cycloaddition reactions. Thus, nitro compounds play important roles in the chemistry of cycloaddition reactions. In this chapter, recent developments of cycloaddition chemistry of nitro compounds and their derivatives are summarized. 

Isoxazolines are good precursors of a,(3-unsaturated ketones.63,94 This transformation is useful for synthesis of polyenes. For example, nitrile oxide cycloaddition chemistry is used to prepare 4-oxo-2-alkenylphosphonates, which are useful to synthesize a long polyethylenic unit via Woodworth-Emmons olefination (Eq. 8.66).101... 

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