- Experimental and theoretical rearrangement of N-acyl-2,2- dimethylaziridines in acidic medium
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The acid isomerization of N-acyl-2,2-dimethylaziridines 1 in concentrated sulfuric acid at room temperature leads to oxazolines 2 but the neutral hydrolysis of 1 in pure water at room temperature leads to amidoalcohols 3. However, the use of aqueous solutions of H2SO4 at different concentrations at room temperature leads to a mixture of oxazolines 2, amidoalcohols 3 and allylamides 4 with yields depending on the acidity of the medium and the nature of the acyl group. A mechanism has been suggested to explain the formation of these three products. DFT calculations employing the Gaussian 09 program with DFT/B3LYP methods and 6-311++G(2d,2p) basis set were carried out which gave the most stable geometry as well as their atomic charge distributions of compounds 1-4. [Figure not available: see fulltext.]
- Mhiri, Madiha Kamoun,Aboumessaad, Firas,Efrit, Mohamed Lotfi,Arfaoui, Youssef,Besbes, Néji
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p. 235 - 245
(2016/02/20)
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- Copper-catalyzed aerobic aliphatic C-H oxygenation directed by an amidine moiety
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A method for the oxygenation of tertiary C-H bonds of N-alkylamidines and N-(2-alkylaryl)amidines is described that utilizes the CuBr?SMe 2/2,2′-bipyridine catalytic system under an O2 atmosphere and provides dihydrooxazoles and 4H-1,3-benzoxazines. The oxygen atom is incorporated from atmospheric molecular oxygen during the present process.
- Wang, Yi-Feng,Chen, Hui,Zhu, Xu,Chiba, Shunsuke
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p. 11980 - 11983
(2012/09/08)
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- Isomerisation catalysee par le gel de silice et L'argile activee de N-Acyl-2,2-Dimethylaziridines: Approche mecanistique
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Silica gel and activated clay, behaving as Lewis acids, reacted with N-acyl-2,2-dimethylaziridines 1 to lead to pentacoordinated aziridinium silicate ions. The regiospecific ring opening on the CMe2 carbon side of the intermediate I involves, after remova
- Besbes, Neji,Jellali, Houyem,Pale, Patrick,Efrit, Mohamed Lotfi,Srasra, Ezzeddine
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scheme or table
p. 883 - 889
(2010/07/05)
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- Aziridines. 76: Neglected aspects of anthracenide (anthracenidyl) chemistry - Reactions with two N-benzoylaziridines
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Reaction of anthracenide A.- with N-benzoylaziridines 1a,b forms charged radicals 3a,b by single electron transfer and homolytic ring opening. Reactions follow that are known or expected as e.g. coupling with position 9 of A.- forming dihydroanthracene anions 9a,b that yield amidoethylated dihydroanthracenes 10a,b, or react with 1a,b giving finally 9,10-bis-amidoethylated dihydroanthracenes 11a,b. Results depend on experimental conditions and on the counter ions Na+ or Li+. Coupling is not regiospecific: contributions by positions 2 and 1 reach 29% or 4%, respectively, of total coupling with the primary radical 3a; much higher 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. Wiley-VCH Verlag GmbH, 2000.
- Lin, Pen-Yuan,Weiss, Rainer,Werry, Juergen,Falkenstein, Reinhard,Stamm, Helmut
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p. 153 - 161
(2007/10/03)
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- Competition in the sodium iodide catalysed isomerisation of some aziridines
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N-Acyl-2,2-dimethylaziridines have been shown to be isomerised by sodium iodide info three isomers. The yield of these isomers appears to depend on the electronic effect of the acyl group.
- Besbes, Neji
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p. 4275 - 4276
(2007/10/03)
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- Reactions of N-acylaziridines with sodium metal and sodium naphthalenide. Elimination of olefines
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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. Johann Ambrosius Barth 1996.
- Lin, Pen-Yuan,Bellos, Konstantinos,Werry, Juergen,Assithianakis, Petros,Weiss, Rainer,Mall, Thomas,Bentz, Gunther,Stamm, Helmut
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p. 270 - 278
(2007/10/03)
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- Friedel-Crafts reactions of some N-acylaziridines: Oxazolines as intermediates
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Without heat supply, AlCl3 and 3-substituted 1-acyl-2-phenylaziridines 1a,b, and 2b in benzene provided the respective Friedel-Crafts products 3a,b, and 4b (acylated 1-substituted 2,2-diphenylethylamines) which in part were further converted to 1,1,2,2-teraphenylethane (5). Oxazolines 6a,b, and 7b were also found. It is shown by means of 2,4,5-triphenyloxazoline 6b that oxazolines are intermediates for 3, 4, and 5. The uncommon heterolysis of these particular oxazolines is discussed.
- Mall,Buchholz,Stamm
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p. 377 - 380
(2007/10/02)
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- Organoselenium- and Proton-Mediated Cyclization Reactions of Allylic Amides and Thioamides. Syntheses of 2-Oxazolines and 2-Thiazolines
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A variety of allylic amides and thioamides were treated with phenylselenenyl bromide in chloroform to give, via 5-exo cyclization, 2-oxazolines and 2-thiazolines, respectively, carrying a (phenylselenenyl)methyl substituent in the 5-position.In some cases (N-crotyl- and N-cinnamylamides/thioamides), dihydro-1,3-oxazines/-thiazines were formed via 6-endo cyclization.The phenylselenenyl group of the cyclofunctionalization products was slowly eliminated by treatment with m-chloroperbenzoic acid to introduce unsaturation in the resulting oxazoline/thiazoline.Reductive removal of the phenylselenenyl group was effected by treatment with triphenyltin hydride.This reaction was sometimes accompanied by a rearrangement of the heterocyclic ring.Proton-induced cyclizations of allylic thioamides to give 2-thiazolines was slowly but efficiently effected in boiling toluene containing a catalytic amount of p-toluenesulfonic acid.
- Engman, Lars
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p. 3425 - 3430
(2007/10/02)
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- REDUCTIVE RING OPENING OF N-ACYLAZIRIDINES: DIFFERENT OUTCOMES OF CHEMICAL AND ELECTROCHEMICAL REACTIONS
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Main products from electrochemical reduction of two N-acylaziridines are the corresponding oxazolines which are not formed in chemical reduction, probably due to a coordination of the oxygen with a metal counter-ion.
- Archier-Jay, D.,Besbes, N.,Laurent, A.,Laurent, E.,Stamm, H.,Tardivel, R.
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p. 2271 - 2272
(2007/10/02)
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- Evolutions differentes de radicaux anions formes par voie chimique ou electrochimique
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Chemical and electrochemical reductions of N-aroylaziridines 1 are described and compared.The first step is a single electron transfer (1 +e -> 1-. -> 1'-.).But compounds obtained from 1'-. are depending on the method used way followed: chemical reduction of N-cinnamoylaziridine 1e provides pyrrolidone 10e; but oxazoline 11e is available by electrochemical reduction of the same starting material 1e.Counter ion seems responsible of these different results.In agreement with this hypothesis, it is shown that pyrrolidone 10e is obtained from 1j only in presence of a counter ion.
- Archier-Jay, Danielle,Besbes, Neji,Laurent, Andre,Laurent, Eliane,Lesniak, Stanislaw,Tardivel, Robert
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p. 537 - 543
(2007/10/02)
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- Reactions with Aziridines, 41. - Highly Regioselective (Abnormal) Ring Opening of 1-Benzoyl-2,2-dimethylaziridine by Simple Nitrile Anions
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The anions 3a-e of the acetonitriles 2a-e cleave the aziridine ring of 1-benzoyl-2,2-dimethylaziridine (1) at the tertiary C-atom (abnormal opening) and provide in this way good yields of the 4-(benzoylamino)-3,3-dimethylbutyronitriles 5a-e and of the 2-(benzoylimino)pyrrolidine 7a, respectively.Positional isomers could not be detected.
- Assithianakis, Petros,Stamm, Helmut
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p. 855 - 858
(2007/10/02)
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- ACTION DES ORGANOMETALLIQUES SUR LES IMINOETHERS : NOUVELLE VOIE D'ACCES AUX OXAZOLINES.
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Iminoethers of type 1 have been shown to react with organometallic reagents to give oxazolines in good yield.The process of the reaction is discussed.
- Bellassoued, M.,Gaudemar, M.,Hajjem, B.,Baccar, B.
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- Highly Regioselective Ring Cleavage of N-Acylaziridines by "Anthracene Hydride" (Anion of 9,10-Dihydroanthracene). Intermediacy of a Carbonyl Adduct. Influence of Nitrogen Inversion on the Ring Opening?
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Anthracene hydride AH- reacts with N-acylaziridines by reductive opening of the aziridine ring and/or amidoethylation of AH-.When the two aziridine carbons are differently substituted, in both reactions only that bond is broken which can form the more stable carbon radical quite in accord with the intermediacy of a radical anion (ketyl) 14 and with the known homolytic cleavage of 14 forming the radical 15.The extra electron in 14 is provided by AH- being oxidized to the radical AH., which can react with 15 either by radical combination or by hydrogen transfer.The reaction of AH- with N-aroylaziridines can be interrupted at the stage of the carbonyl adduct 5 as is shown by the isolation of the ketones 7a,b.So, 5 (R4 = aryl) is considered to be in equilibrium with the radical pair AH./14.The conversion of 5 into the final products progresses as expected from its structure apart from the observed retardation by a phenyl substituent in the aziridine ring (3a, 4a).This retardation is tentatively explained by a hypothesis assuming ring opening of 14 to occur in the transition state of nitrogen inversion.The anion X- of xanthene resembles AH- in its reactivity.Both carbanions react with N-sulfonylaziridines as expected from an SN2 mechanism.
- Stamm, Helmut,Sommer, Andreas,Woderer, Anton,Wiesert, Wolfgang,Mall, Thomas,Assithianakis, Petros
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p. 4946 - 4955
(2007/10/02)
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