Friedel‐Crafts‐Reaktion einiger N‐Acylaziridine: Oxazoline als Zwischenstufen

Abstract

Without heat supply, AIC13 and 3-substituted 1-acyl-2-phenylaziridines la,b, and 2b in benzene provided the respective Friedel-Crufts products 3a,b, and 4b (acylated 1 -substituted 2,2-diphenylethylamines) which in part were further converted to 1,1,2.2-tetraphenylethane (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.

Electrostatic repulsion by the charged tail of a radical controls the stereochemistry of coupling with anthracenide. Reversibility of benzylic fragmentation 1,2

“…The IR carbonyl bands 14 confirm the expectation that cis-4a (1683 cm Ϫ1 ) has a steeper nitrogen pyramid than trans-4a (1664 ). The S N 2-reactivity of acylaziridines decreases when the steepness of the nitrogen pyramid increases.…”

“…Aziridines cis-4a and trans-4a are known. 14 [ 2 H 4 ]AH 2 was prepared from AH 2 and [ 2 H 6 ]DMSO 6 as described in ref. 19.…”

Nucleophilic ring opening of aziridines

“…open-chain products, as is shown in Scheme 29 for 107b,d and 110b [91]. Even without application of heat, most of the arising 148 is converted to 149 under the experimental conditions.…”

“…Scheme 21) arise by real NRO from AHand the following Az's: cis/trans-107d[68], cis/ trans-107a[69], 110 (Y = CO-1-adamantyl) [53b],…”

Benzylic Fragmentation (BFR), an Aromatic Analogue of E1cB Including a Homolytic Variant, as either Nucleofugal or Homolytic Path to Aryl Stabilized Carbanions or Ketyls, respectively

“…With prolonged reaction 7 undergoes BFR quantitatively, but with Li + the yield (up to 66% with Na + ) of 9 is less than the yield of A due to a slow elimination of Li 2 O from 8(Li + ) 2 as follows from comparison with the behaviour of trans-10 (M = O): its reaction gives a high yield of 1,2-diphenylethanol with Na + only while with Li + the deficit is made up by trans-stilbene. For the same reaction with 10 (M = NTs) the analogue of 7 arises (stereospecifically from cis-and trans-10) in good yield but the only identifiable product from subsequent BFR is trans-stilbene [6]. The reaction of 6 shows nicely how nucleophilic attack controls the site of overall reduction via BFR: the exocyclic bond in the isomer of 7 is stable.…”