Three-Membered Azaheterocycles

One of the features of a,/3-unsaturated ketones is the presence of two electrophilic centers. Because of this feature, reactions with binucleophiles can proceed as a 1,2-addition or as a 1,4-addition. Regarding three-membered nitrogen-containing heterocycles formed from a,/3-unsaturated ketones and their derivatives, the unsaturated ketone acts either as a 1,2-bielectrophile (substituted ethylene), which leads to the formation of ethyleneimines, or as a 1,4-bielectrophile, giving rise to either bi- or tricyclic aziridines. Hence, the present chapter is divided into two parts, one which is entirely dedicated to aziridinyl ketones and the other to bi- and tricyclic aziridines. 

Fused aziridines are interesting compounds owing to the fact that the strained three-membered ring can easily open and cause dipolar cycloaddition reactions as well as their photochromic properties. Therefore, most of this chapter covers the chemical and photochemical properties of bi- and tricyclic aziridines. Some properties of aziridinyl ketones are also reviewed, in particular, reactions leading to aziridinyl anils. 

1 Synthesis of Aziridinyl Ketones and Their Chemical Properties 

Methods of obtaining aziridine derivatives from a,/3-unsaturated ketones can be divided into two basic groups one-pot synthesis directly from an unsaturated ketone or stepwise synthesis involving the initial modification of a double bond. 

Chebanov et al., Azaheterocycles Based on a,/3-Unsaturated Carbonyls, Springer-Verlag Berlin Heidelberg 2008 

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