126179-55-3Relevant articles and documents
Reactions of N-acylaziridines with sodium metal and sodium naphthalenide. Elimination of olefines
Lin, Pen-Yuan,Bellos, Konstantinos,Werry, Juergen,Assithianakis, Petros,Weiss, Rainer,Mall, Thomas,Bentz, Gunther,Stamm, Helmut
, p. 270 - 278 (2007/10/03)
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.
HOMOLYTIC AZIRIDINE OPENING (AZA VARIANT OF CYCLOPROPYLCARBINYL-HOMOALLYL REARRANGEMENT) BY ADDITION OF TRIBUTYLTIN RADICAL TO N-ACYLAZIRIDINES. FACTORS CONTRIBUTING TO THE REGIOSELECTIVITY
Werry, Juergen,Stamm, Helmut,Lin, Pen-Yuan,Falkenstein, Reinhard,Gries, Stefan,Irngartinger, Hermann
, p. 5015 - 5028 (2007/10/02)
AIBN initiated reaction of N-acylaziridines 1 with Bu3SnH in refluxing benzene provided products 5 and 8 of reductive ring opening.Yields (practically quantitative in most cases) fell drastically with steric hindrance of the addition of Bu3Sn to the acyl oxygen of 1.They depended to some extent on the experimental conditions for hydrogen capturing when aziridine homolysis provided a primary radical 3 or 6.The regioselectivity of (probably reversible) ring homolysis can be understood in terms of the stability of the arising radical (3, 6), of stereoelectronic control (e.g. 1i as compared to 1h) and of frontier orbital interactions (1j).A possible difference in bond lengths as explanation for the formation of the primary radical from 1j did not find support from an X-ray structure analysis of N-tosyl-2-methyl-aziridine 11.Isomeric products were obtained only twice (1i, 1j) with a dependence of the ratio 5j:8j on concentration and hydrogen isotope of Bu3SnH.No such dependence was found for the ratio 5:14 (reduction without and with an intervening cyclization of 3 leading to a pyrrolidone) obtained from the N-cinnamoylaziridine 1l.This ratio (1:9 for 1l and 1:3 for 1n) must reflect the E-Z isomers in 3.The observed preference for the formation of E-3 from 2 can be explained by stereoelectronic and steric effects.A cinnamoyl double bond in 5 was saturated depending on experimental conditions.
