Reactions of N‐acylaziridines 1a–g (N‐benzoyl except 1d) with sodium or naphthalenide N.− in THF provide a variety of products that usually arise via the aziridino ketyls 2. Homolytic ring opening of 2 generates the amidatoalkyl radicals 3. Only with a very short reaction time were small amounts of benzil or benzoylnaphthalenes obtained indicating a reversible trapping of 2 by dimerization or coupling with N.−. Homolysis of 2 produced always the more stable 3 apart from reactions of monomethylaziridines 1c,d where the primary radical i‐3c,d is kinetically favoured. The amides R1CONHCHR4CHR2R3 (9, isopropylamides i‐9c,d from 1c,d) were usually the main products. 9 arise from 3 either by H atom abstraction from THF (probably in sodium metal runs) or by reduction of 3 to carbanions 5 that abstract a proton from THF (N.− runs). Addition of 5a (R2−4 = H) to 1a gives finally the ketone 8a. Self reaction of primary radical 3a is dimerization. Self reaction of tertiary or secondary radicals is disproportionation when an allylamide arises. This isomerizes to an enamide unless it is conjugated. R2R3CCHR4 and R1CONH2 arise (probably) always. The mechanism, possibly a cyclic process of anion 6, is not clear.

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153Single electron transfer (SET) reactions of N-acylaziridines with radical anions and other electron sources were prompted by a mechanistic problem [2]. Usually aziridino ketyls arise and homolyze to amidatoalkyl radicals [2 -7]. The final result can depend on substituents of the aziridine ring, on the acyl group and on the radical anion. 2-Phenylaziridines present a special case [6 -7]. Reactions with N-pivaloylaziridines were reported both with naphthalenidyl N ·¯ (naphthalenide) and with A ·[ 3], reactions of N-aroylaziridines with N ·¯ only [5]. After a very short notice [2], reactions of 1a,b with A ·ā re now fully described with steps and types of products usually ignored or even unknown in A ·¯ chemistry and therefore of possible importance for reactions with alkylating agents RX [8] (cf. introduction in [3]) that give alkylation in position 9 (and 10) of A ·¯ besides reduction (→ RH) and multi-step dimerization (→ RR) (Scheme 1). Tables 1 and 2 Table 1 indicates that this nearly insoluble product may have been lost during work-up [5]. This does not disturb a discussion of the other products. Counter ion Na + has been replaced by Li + in runs 6 and 7 that are dealt with separately. Results and DiscussionThe product of two-fold SET (6a) was always the main product of Table 1 in contrast to the results from reactions of A ·¯ with RX [8] -pivaloylaziridines [3]. This is in accord with the electron source 2a for the conversion 3a → 4a since 2a has a longer lifetime than aliphatic aziridino ketyls and can better compete with A ·¯. This SET from 2a to 3a may further profit from the reported [5] reversible dimerization of 2a if one ketyl of the separating pair undergoes ring opening before it diffuses away. The yields of 6a (and also of 6b in Table 2) may be a bit low in long term runs since 5a,b and analogous precursors can eliminate [5] the Nsubstituent as olefine (ethene from 5a) when Na + is the counter ion.or with Nhigher contributions are possible with Li. Product 21s (probably 3,3'-disubstituted tetrahydrobianthryl) may arise by hydrogen detachment from the first intermediate (29) of coupling with position 2 and dimerization of the formed 2-substituted A ·¯ (30). Coupling products may be fully aromatized or may be hydroxylated in one of the benzylic positions. With counter ion Li + a non-SET reaction of 1a with the dimer of A ·¯ is indicated by the isolation of 9-benzoyl-dihydroanthracene 15 and by 19% yield of 16a (aromatized 10a). Reaction of 3b with anthracene is indicated by 10,10'-disubstituted tetrahydrobianthryl 37.

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