[3+2] Cycloadditions and nucleophilic additions of aziridines under CC and CN bond cleavage

Radical Cations of Phenyl‐Substituted Aziridines: What Are the Conditions for Ring Opening?

“…[20] In aqueous solution 2a +• and 3b +• are trapped faster by oxygen than the radical cations of the 1-aryl aziridines and, in contrast to the latter, 3b +• is quenchable with oxygen even in nbutyl chloride. The fact that 3b was found to undergo [3+2] cycloadditions with various dipolarophiles under PET-conditions [6,7,[10][11][12][13] also speaks for a ring opened structure of the radical cation. .…”

“…[11,37] Starting with commercial available styrol oxide the corresponding -amino alcohol is prepared according to the procedure of Chapman and Triggle. [38] The formation of 1-butyl-2-phenyl aziridine occured as described by Okada et al [37] Preparation of 1-butyl-trans-2,3-diphenyl aziridine (3b).…”

“…[38] The formation of 1-butyl-2-phenyl aziridine occured as described by Okada et al [37] Preparation of 1-butyl-trans-2,3-diphenyl aziridine (3b). [11] Using trans-stilbene as starting material epoxidation with MCPBA formed the corresponding trans-stilbene oxide in yields of 75 %. Following the procedure of Deyrup and Moyer [39] the epoxide is opened to the -amino alcohol.…”

“…This conclusion is confirmed by preparative studies which yielded no products from reactions with dipolarophiles, products that would have indicated that ring opening to azomethine ylide radical cations has occurred, under PET-conditions. [11] 1,2,3-Triphenylaziridine 5…”

“…[3][4][5] Under photoinduced electron transfer (PET) conditions the aziridine is oxidized to the corresponding radical cation, which can react in a similar manner. [6][7][8][9][10] In the course of our investigations aimed at the applications of aziridines in organic synthesis [10,11] we became interested in the reactive intermediates of the [3+2] cycloadditions, i.e. the azomethine ylides and the radical cations of the aziridines, to elucidate the mechanisms of the reactions.…”