Carbanions aziridinyl

There are at least two mechanisms available for aziridine cis-trans isomerism. The first is base-catalyzed and proceeds via an intermediate carbanion (235). The second mechanism can be either thermally or photochemically initiated and proceeds by way of an intermediate azomethine ylide. The absence of a catalytic effect and interception of the 1,3-dipole intermediate provide support for this route. A variety of aziridinyl ketones have been found to undergo equilibration when subjected to base-catalyzed conditions (65JA1050). In most of these cases the cis isomer is more stable than the trans. Base-catalyzed isotope exchange has also been observed in at least one molecule which lacks a stabilizing carbonyl group (72TL3591). 

Aziridines can also be employed as nucleophiles. When one of the carbon atoms in the aziridine ring is equipped with an electron-withdrawing substituent, these substrates can often be cleanly deprotonated and used for subsequent carbanion chemistry. For example, the anion derived from the trifluoromethyl aziridine 162 engages in nucleophilic addition onto benzaldehyde to give the aziridinyl alcohol 163 in 83% yield <03TL6319>. Similarly, deprotonation of the oxazolinylaziridine 164 followed by treatment with methyl iodide gave mainly the methylated product 165 <03TL2677>. 

Aziridinyl carbanion with electron-withdrawing substituent... 

Stable aziridinyl carbanions (648) have been prepared by treating the corresponding aziridine with sodium hydride in HMPA. ... 

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