ChemInform Abstract: STUDY OF THE FORMATION OF OXAZOLES FROM SUBSTITUTED 2‐ARYL‐1‐PHTHALIMIDOAZIRIDINES

Abstract

2‐Ary1‐ 1‐phthalimido‐aziridine, die in 3‐Stellung durch zwei elektrophile Gruppen substituiert sind (von denen wenigstens eine eine Carbonylgruppe enthält), zersetzen sich thermisch durch zwei miteinander konkurrierende.

Synthesis and photolysis of N-phthalimidoaziridines with electron-withdrawing substituents

“…Aziridine 1 (775 mg, 85%) was obtained, the analytical characteristics of which agreed completely with the literature data of [13]. 13 C NMR spectrum (CDCl 3 ), δ, ppm: 43.45 (C (2,8) ); 46.59 (CH 2 ); 50.85 (C (1, 9) and C (4,6) ); 123.83 (C (b) ); 129.89 (C (a) ); 134.87 (C (c) ); 137.14 (C (10,11) (2,7) , and C (9,11) ); 123.39 (C (b) ); 130.63 (C (a) ); 134.46 (C (c) ); 142.48 (C (4,5) 13 C NMR spectrum (mixture of DMSO-d 6 -CCl 4 , ~1:2), δ, ppm: 24.72 (CH 2 ); 37.49 (C (1, 9) ); 41.39 (C (2,8) ); 49.22 (C (4,6) ); 52.36 (C (10,12) ); 122.28 and 122.89 (C (b,b') ); 129.53 and 129.82 (C (a,a') ); 133.69 and 134. N-Aminophthalimide (486 mg, 3 mmol) and lead tetraacetate (1.33 g, 3 mmol) were added alternately in 10-15 mg portions during 40 min to a suspension of anhydrous potassium carbonate (1.3 g, 9.4 mmol) in a mixture of ethyl cinnamate (792 mg, 4.5 mmol) and methylene chloride (40 ml) cooled to 0°C.…”

“…in the presence of 1,3-dipolarophiles give good yields of products, the formation of which is treated as the result of an intra-(oxazolines, oxazoles) and/or intermolecular (pyrrolines, azetidines) conversion of the corresponding N-phthalimidoazomethinylides [4][5][6]. These reactive intermediates enter into various subsequent conversions, though their addition at the multiple bond of 1,3-dipolarophiles has undoubted preparative value as a general method of synthesizing five-membered nitrogen heterocycles of type C [1-3].…”

Intra- and intermolecular thermal transformations of 2-acyl- and 2-alkoxycarbonyl-N-phthalimidoaziridines

“…The invertomers of aziridine 1e exist in comparable amounts since the effective volumes of the substituents at the carbon atoms of the aziridine ring in this case are similar (both substituents have a carbonyl group next to the three-membered ring). The coupling constants of compounds 1a,d, and 1e (4.4-4.9 Hz for the major invertomer and 4.7-5.8 Hz for the minor invertomer) indicate trans arrangement of the aziridine protons, which is in accord with the well-known steric specificity of oxidative aminoaziridination [3][4][5][6][7][8][9][10]. We should also note that the signals of the phthalimide group carbon atoms in the 13 C NMR spectra of aziridines 1a-f are broadened as a consequence of a second hindered process, which is slow on the NMR time scale, namely, rotation about the tetrasubstituted N-N bond [4,5,10].…”

Amination of CF3-Enones with Nosyloxycarbamates

“…As shown in Table , acyl olefin 3 gives the expected corresponding trans -aziridine 9 by an aza-MIRC (Michael-initiated ring closure) reaction, as confirmed by the typical aziridine 1 H NMR signals at δ 3.33 and 3.66. On the contrary, fluorinated olefins 1 and 2 give 5-trifluoromethyl-substituted 2,3-dihydrooxazoles (4-oxazolines) 6 , 7 , and 8 probably through a domino reaction involving a fast rearrangement of unstable 2-trifluoroacetyl aziridines I (Scheme ) . The presence of singlet signals at δ 6.67−6.92 in the 1 H NMR of 6 − 8 confirms the structure of the 4-oxazoline ring.…”