Aziridines, substituted preparation

Chiral thiazole substituted aziridines are prepared in a diastereoselective fashion by adding lithiated (a-chloroalkyl)thiazoles to chiral imines <04T1175>. For example, treatment of racemic thiazole 115 with LDA and chiral imine 114 provides 116 in high diastereoselectivity. 

Aziridines.—Reviews on general methods of aziridine synthesis and the preparation and properties of aziridine-substituted fatty acids have appeared. 

Similarly 2- and 4-disubstituted seienazolidines were prepared from 2-methyl- and 2,2-dimethylaziridines (Table X-17i (74) and 2- and 3-disubstituted seienazolidines were obtained from N-substituted aziridines (Table X-18) (74). 

The generality of this method for large-scale preparations was demonstrated for the syntheses of toluenesulfonyl aziridines from aminohydroxylation products of N-substituted cinnamamides (Table 12.9). The results of synthesis of other sulfo-nyl aziridines are summarized in Tables 12.10 and 12.11. 

The aminotin compounds are less readily prepared, and are more reactive both in substitution and addition processes, than the alkox-ides. The established routes to, and reactions of, these compounds are exemplified by recent work on the aziridine derivatives (217). 

The highly strained and reactive 2iT-azirines have been extensively studied for various synthetic purposes, such as ring expansion reactions, cycloaddition reactions, preparation of functionalized amines and substituted aziridines. The older literature on azirines in synthesis has extensively been reviewed [69]. Concerning azirines with defined chirality only scarce information is available. Practically all reactions of azirines take place at the activated imine bond. Reduction with sodium borohydride leads to cz5-substituted aziridines as is shown in Scheme 48 [26,28]. 

N,N-Dibenzyl (z -amino a-chloroketimines 202 can be prepared from the corresponding ketones, which in turn are available by the addition of chloromethyllithium to esters of natural cz-amino acids. Reduction of 202 with sodium cyanoborohydride directly afforded a-aminoalkyl-substituted aziridines 203 with high syn diastereoselectivity, which was only moderately affected by the size of the substituent [96] (Scheme 30). A complemen-... 

The JV-benzyl aziridines 69, 92-95 which differ only in the nature of the norbomane bridge (CH2, spirocyclopropyl, isopropylidene, oxygen, substituted nitrogen) (Scheme 14), have been prepared and reacted with each of the corresponding benzonorbomadienes 36-40 from which they were derived. All 25 reactions were conducted to produce 14 of the possible 15 different... 

The synthetic applications of substituted 1,2,3-triazole 1-oxides and 1,2,3-triazolium-l-imides in the preparations of 1,2,3-triazines, 1,3,4,5-oxo- and -thia-triazines, and 1,2,3,5-tetrazines have been discussed in Section 4.01.4.12. Conversions of 1,2,3-triazolines into aziridines either thermally or photochemically were described in detail in CHEC-I <84CHEC-1(5)691 > and in a review <84AHC(37)217>. Some recent developments are discussed in Section 4.01.5. 

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