82495-90-7Relevant academic research and scientific papers
Three positional isomers of substituted triphenylmethanes from reactions of trityl anion with 1-acyl-2,2-dimethylaziridines
Werry, Juergen,Lin, Pen-Yuan,Assithianakis, Petros,Stamm, Helmut
, p. 3103 - 3110 (2007/10/03)
Ring opening of aziridines 4a-d in reactions with trityl anion Tr(-) proceeds exclusively by cleavage of the NCMe2 bond.Substitution of the benzylic carbon of Tr(-) leads to 'central' products 10a-d in yields of 0-5percent.This is ascribed to an SN2 reaction with borderline character, as is well known from reactions of aziridines 4a-d with other nucleophiles.All remaining ring-opening reactions result from single-electron transfer (SET).This is direct SET from Tr(-) to aziridines 4a-c.For compound 4d (acyl = cinnamoyl), the SET reaction is of the innersphere type and proceeds via Michael addition, at least in part.Homolytic ring opening of the generated aziridino ketyls 5 forms the tertiary amidatoalkyl radicals 6.Main reaction of radicals 6a-c is transfer of a hydrogen atom from one of its two methyl groups to the generated trityl radical Tr..Methallylamides 7 and enamides 8 are the final products. ortho-Substituted triphenylmethanes 12 and/or its olefinic precursors 13 arise in ca. 20percent yield.A mechanism for the formation of these unique products is proposed that first converts the radicals 6 into the corresponding carbanions 16 which undergo an SN2' reaction with one allylic system TrCHCH=CH* of the dimer 14 of Tr..The leaving group Tr(-) is eliminated from this partial structure when carbanions 16 attack the marked carbon converting it finally into the substituted ortho carbon of compounds 12.Addition of radicals 6 to Tr(-) is probably the way to the para-substituted triphenylmethanes 11, which arise in yields of only 0-1percent from aziridines 4a,b (acyl = benzoyl, pivaloyl).Higher yields of para-substituted compounds 11 are obtained from aziridines 4c (acyl = 4-phenylbenzoyl) and 4d.This is ascribed, at least for substrate 4c, to a chain reaction because ketyl 5c must be formed more rapidly than ketyls 5a,b.A substantial part of radical 6d cyclizes, ending up as the triphenylmethane compound 26 that carries a pyrrolidone ring in the para position.
Radical Combination in the ortho Position of Trityl Radical Observed in Single-electron Transfer Reactions of Trityl Anion
Werry, Juergen,Lin, Pen-Yuan,Bellos, Konstantinos,Assithianakis, Petros,Stamm, Helmut
, p. 1389 - 1390 (2007/10/02)
Single-electron transfer reactions between trityl anion and 1-acyl-2,2-dimethylaziridines provide, among other products, the methallyl amides 7 and the triphenylmethanes 8 carrying an amidoethyl chain attached with the tertiary carbon ortho to the triphen
Reactions with aziridines - 39. Ring opening of activated 2,2-dimethylaziridines by grignard reagents. A mechanistic study
Onistschenko, Andreas,Buchholz, Berthold,Stamm, Helmut
, p. 565 - 576 (2007/10/02)
Reaction of activated 2,2-dimethylaziridines 1 with Grignard reagents RMgHal in boiling THF can yield the products 2 of normal aziridine ring opening, the rearranged opening products 3, and the methallylamides 4 (isomers of 1 ). The product distribution depends on R, Hal, and experimental conditions, and very strongly on the nature of the activating group A. It is shown that 1 is opened (reversibly for A = sulfonyl) forming 10 through a Lewis acid assisted attack of Halθ on the tert carbon of 1 (abnormal opening by Halθ ). Evidence is presented to show that 4 as well as 3 come from this intermediate.
