Three positional isomers of substituted triphenylmethanes from reactions of trityl anion with 1-acyl-2,2-dimethylaziridines

Werry, Jürgen; Lin, Pei‐Wen; Stamm, H.

doi:10.1039/p19950003103

Cited by 5 publications

(4 citation statements)

References 14 publications

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“…Similarly, while indole-Li and 124-S provide only normal N-substitution in THF/ether in accord with a reaction of the highly nucleophilic N-anion, in toluene (no dissociation) this product arises in 29% yield only while substitution in position 3 (very poor Nu -) proceeds with 49% abnormal and 16% normal NRO [71]. The said hypothesis on the abnormal NRO [76] consisted of SET, homolytic ring opening and radical coupling or more complicated processes as realized in reactions of Trwith Az's 124-A (even with 124-Aa) [78] whose three Tr containing products are shown in Sche- [84] no difference in RS for 124-A or other acylaziridines is so far known between products of real NRO and those from all kinds of pseudo NRO but one should be aware that a conformation dependent stereoelectronic effect (cf. [8]) may change RS of homolytic ring opening for trans-Az's of type trans-109b.…”

Section: Scheme 19 C-amidoethylation Of Simple Nitrilesmentioning

confidence: 80%

“…LG quality of 124-N resembles that one of 124-A: pK a of dinitroaniline is 16 [77]. Normal products are obtained (Scheme 24) from 124-S and 52a (→ 125) [72], Tr - [78], X -(products of type 81 and 82) [53a], Fl -(products of type 81 and 82) [79], anion of carbazole [79], AH -("mono" and "bis" product of Scheme 16, only "mono" at low temp.) [53a], aliphatic amines [80] and RO - [6].…”

Section: Scheme 19 C-amidoethylation Of Simple Nitrilesmentioning

confidence: 95%

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Nucleophilic ring opening of aziridines

Stamm

1999

J. prakt. Chem.

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102

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This account of research work on nucleophilic ring opening (NRO) of aziridines (Az's) demonstrates the broad synthetic scope of this reaction, inclusive secondary reactions, and it discusses the special mechanistic fundamentals and details as well as mechanistic variants. Formation of a C–C bond by NRO is the red thread in this report. A central mechanistic aspect is the quality of the leaving group in Az bases, aziridinium ions and activated Az's (acyl, sulfonyl; double activation). Factors controlling the regioselectivity of NRO are dealt with as well as the influence of the nitrogen pyramid. Competing reactions include carbonyl attack (acylated Az's) and electron transfer with cases of pseudo‐NRO (multistep radical paths).

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Section: Scheme 19 C-amidoethylation Of Simple Nitrilesmentioning

confidence: 80%

Section: Scheme 19 C-amidoethylation Of Simple Nitrilesmentioning

confidence: 95%

Nucleophilic ring opening of aziridines

Stamm

1999

J. prakt. Chem.

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102

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“…Except for run 13, 6b was not the main product, even taken together with 32 and 33. The tertiary radical 3b does not dimerize; its self reaction is disproportionation to 5b and 31, the precursor of 32 and 33 (via slow base catalyzed isomerization of 31 [16]). It is not clear how much of 32 is an artifact of 1a.…”

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confidence: 99%

Neglected Aspects of Anthracenide (Anthracenidyl) Chemistry — Reactions with twoN-Benzoylaziridines

et al. 2000

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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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“…N -Activated aziridines are regarded versatile pseudohalides, and their catalytic asymmetric ring-opening reactions with carbon nucleophiles provide useful tools for the synthesis of various nitrogen-containing biologically active compounds. − In consideration of the prominent reactivity of such aziridines, we attempted the reaction of racemic N -sulfonyl 2-methyl-2-phenylaziridine 2 with 3-methyloxindole 3a (Table ). Thus, 3a was treated with 2 equiv of racemic N -tosyl aziridine 2a in the presence of l -alanine-derived chiral 1,2,3-triazolium bromide 1a·Br (5 mol %) and K 2 CO 3 (1 equiv) in Et 2 O at room temperature for 24 h. The ring-opening substitution occurred exclusively at the fully substituted carbon to give alkylation product 4a , which had adjacent quaternary chiral carbons, in 78% yield (entry 1).…”

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confidence: 99%