Azomethine ylide chemistry

In this section, those reactions in which the ylide is attached by a tether to the dipolaraphile resulting in an intramolecular cycloaddition will be discussed. To date, such a strategy has proved to be one of the less investigated aspects of azomethine ylide chemistry. However, intramolecular azomethine ylide technology, when combined with the excellent stereocontrol offered by cycloaddition reactions, allows for the rapid construction of complex polycyclic systems from relatively simple precursors. Consequently, it represents a highly attractive synthetic protocol that makes it a candidate for further investigation in the coming years. 

Metal-mediated processes represent an important advance in azomethine ylide chemistry, allowing reactions to proceed at ambient temperatures. They also allow for the possibility of chiral catalysis, which is a little explored area as yet, but represents an exciting development allowing for the induction of enantiocontrol without the need for stoichiometric stereocontrolling units. 

Although Grigg et al. (97) have been prolific authors in azomethine ylide chemistry, probably their greatest contribution has been in the development of metal-mediated technologies, leading to elegant solutions to the problems of regio-, stereo-, and enantiocontrol over reactions. Typically, EtaN or DBU deprotonation of amino esters, with subsequent metalation of the anion, led to the formation of stabilized, metallo-1,3-dipolar systems (340), often to the extent where isolation is possible (Scheme 3.115). 

O. Tsuge and S. Kanemasa, Recent Advances in Azomethine Ylide Chemistry, in Advances in Heterocyclic Chemistry, Vol. 45, A. R. Katritzky, ed., Academic Press, San Diego, 1989, pp. 232-349. 

Tsuge, O., Kanemasa, S., Recent Advances in Azomethine Ylide Chemistry, 45, 231. 

Azoles, basicity and acidity of, 41, 187 Azomethine ylide chemistry, recent advances in, 45, 231... 

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