50688-77-2Relevant articles and documents
Aziridines. 76: Neglected aspects of anthracenide (anthracenidyl) chemistry - Reactions with two N-benzoylaziridines
Lin, Pen-Yuan,Weiss, Rainer,Werry, Juergen,Falkenstein, Reinhard,Stamm, Helmut
, p. 153 - 161 (2007/10/03)
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.
Reactions of Carbanions with two Sterically Demanding 1-Benzoylaziridines: SET, SN2, Carbonyl Attack.
Bellos, Konstantinos,Stamm, Helmut
, p. 269 - 273 (2007/10/02)
Reactions of 2-phenyl (1a) and 2-benzyl (1b) 1-benzoyl-2-butylaziridines with carbanions X-, AH-, and Fl- of xanthene, dihydroanthracene and fluorene always form N-(2-butylethyl)-benzamides carrying phenyl (9a) or benzyl (9b).This reductive ring opening indicates an SET mechanism with aziridino ketyls 6a,b as intermediates.Nucleophilic ring opening (SNs) is found only with the carbanion of the lowest reducing power: Fl- 5a,b (62percent, 14percent).These two mechanisms cleave different bonds, a finding without precedence in SN2/SET competitions.Carbonyl addition resulting in benzoyl transfer to xanthene, dihydroanthracene or fluorene is usually also observed.It is the main reaction with X- and 1a.The highest yields of 9a,b are obtained with AH- since a special inner-sphere SET is available.
Reductive Ring Opening of N-Benzoylaziridine by Anthracene Hydride (Anion of 9,10-Dihydroanthracene) via Base-Induced Fragmentation of the Intermediate Carbonyl Adduct
Stamm, Helmut,Mall, Thomas,Falkenstein, Reinhard,Werry, Juergen,Speth, Dieter
, p. 1603 - 1607 (2007/10/02)
As previously reported reaction of anthracene hydride (AH-) or of its oxa analogue xanthenyl anion (X-), with N-benzoylaziridines 1a,b can result in amidoethylation (2a,b and 3a,b) of the carboanion, in reductive opening (4a,b) of the aziridine ring, and in attack on the carbonyl group of 1a,b.We now show with 1a that both the rate of ring opening and the amount of reductive opening are significantly enhanced by an excess of AH-Li+ while the initially formed (90percent) carbonyl adduct 6a survives with a defict of AH-Li+.Both effects due to carbanion excess are absent with X-Li+ but are much stronger with AH-Na+.These results point to a rapid process that is triggered off by deprotonation at position 10 of the carbonyl adduct 6.A concerted or subsequent homolytic fragmentation is proposed to generate the ketyl 5 of 1, followed by homolytic ring opening of 5 to yield the radical 12, which is reduced to the carbanion 14.The latter forms 4 by capturing a proton from dihydroantracene.Inaccessibility of reductive ring opening for a trialkylacetyl-activated aziridine is demonstrated again (18).
