(3aR',4R',6S',6aS')-4-Acetyl-2,6-diphenyl-5-phthalimidotetrahydropyrrolo[3,4-c]pyrrole-1,3(2H,3aH)-
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dione (4a) was obtained as colorless crystals, mp 231-232°C. H NMR spectrum, , ppm (J, Hz): 2.55 (3H, s,
CH3); 3.58 (1H, dd, J = 9.3, J = 7.2, H-6a); 4.03 (1H, dd, J = 9.3, J = 4.9, H-3a); 4.72 (1H, d, J = 4.9, H-4); 5.13
(1H, d, J = 7.2, H-6); 7.28-7.64 (10H, m, 2C6H5); 7.71-7.80 (4H, m, PhthN). 13C NMR spectrum, , ppm: 27.34
(CH3); 45.75 and 52.33 (C-3a, C-6a); 71.42 and 73.26 (C-4, C-6); 123.93 (C-b); 126.78, 127.19, 128.96, 129.41
(C-m, C-o); 128.65 and 129.04 (C-p); 129.56 (C-a); 131.88 (2-Ph, C-ipso); 134.87 (C-c); 138.36 (6-Ph, C-ipso);
175.10 and 175.82 (C-1, C-3); 203.68 (CO). The phthalimide NCO signals are not visible due to strong
broadening. Found: 480.1529 [M+H]+. Calculated: [M+H]+ 480.1554. Found, %: C 69.70; H 4.26; N 8.67.
C28H21N3O5. Calculated, %: C 70.14; H 4.42; N 8.76.
5-Methyl-2-phenyloxazole (3a) was obtained as a colorless oil. 1H NMR spectrum, , ppm: 2.39 (3H, s,
CH3); 6.84 (1H, s, H-4); 7.41-7.46 (3H, m, H-m, H-p); 7.98-8.01 (2H, m, H-o). The spectrum reported by
Herrera et al. [23] is in good accord with these results.
Aziridine 1d was heated for 4 h at 140°C. Chromatographic separation eluting with from 6:1 to 2:1
hexane–ethyl acetate gave 136 mg (48%) adduct 4d and 21 mg (17%) oxazole 3d.
(3aR',4R',6S',6aS')-2,4-Diphenyl-6-[(E)-3-phenylprop-2-enoyl]-5-phthalimidotetrahydropyrrolo-
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[3,4-c]pyrrole-1,3(2H,3aH)-dione (4d) was obtained as colorless crystals, mp 162-163°C. H NMR spectrum,
, ppm (J, Hz): 3.61 (1H, dd, J = 9.4, J = 7.6) and 4.08 (1H, dd, J = 9.4, J = 5.7) (H-3a, H-6a); 5.04 (1H, d,
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J = 5.7) and 5.21 (1H, d, J = 7.6) (H-4, H-6); 7.59-7.82 (21H, m, H arom). C NMR spectrum, , ppm: 46.13
and 51.91 (C-3a, C-6a); 70.89 and 71.67 (C-4, C-6); 122.07 (C-); 126.90, 127.65, 128.84, 129.02, 129.12,
129.14, 129.20, 129.51, 131.20 (C-m, C-o, C-p); 131.96, 134.59, 137.94 (C-ipso); 134.83 (C-c); 145.83 (C-);
175.02, 175.90 (C-1, C-3); 194.48 (CO). The signals for C-a, C-b, and the phthalimide group NCO carbon
atoms are not visible due to strong broadening. Found: m/z 568.1804 [M+H]+. Calculated: [M+H]+ 568.1867.
Found, %: C 74.30; H 4.51, N 7.38. C35H25N3O5. Calculated, %: C 74.06; H 4.44; N 7.40.
Aziridine 1e was heated for 150 min at 200°C. Chromatographic separation eluting with from 6:1 to 2:1
hexane–ethyl acetate gave adduct 4e, which was additionally purified by recrystallization from 8:1 ether–
dichloromethane to give 84 mg (32%) 4e and 26 mg (25%) oxazole 3e.
Methyl Ester of (1R',3S',3aS',6aR')-3-Benzoyl-4,6-dioxo-5-phenyl-2-phthalimdooctahydropyrrolo-
[3,4-c]pyrrole-1-carboxylic Acid (4e) was obtained as colorless crystals, mp 130-132°C. 1H NMR spectrum, ,
ppm (J, Hz): 3.76 (3H, s, CH3); 4.20 (1H, dd, J = 9.6, J = 3.9) and 4.29 (1H, d.d, J = 9.6, J = 4.7 (H-3a, H-6a);
4.54 (1H, d, J = 4.7) and 5.47 (1H, d, J = 3.9) (H-1, H-3); 7.32-7.56 (8H, m, H arom); 7.73-7.82 (4H, m,
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PhthN); 7.92-7.95 (2H, m, PhCO, H-o). C NMR spectrum, , ppm: 47.31, 47.36, 53.33 (CH3, C-3a, C-6a);
69.35 and 70.16 (C-1, C-3); 124.01 (C-b); 126.93, 128.83, 129.10, 129.43, 133.80 (C-m, C-o, C-p); 134.92
(C-c); 129.54 and 135.20 (C-ipso); 169.24, 175.36, 176.14 (CO2, C-4, C-6); 193.80 (CO). The signals for C-a
and the phthalimide group NCO carbon atom are not visible due to strong broadening. Found: m/z 546.1248
[M+Na]+. Calculated: [M+Na]+ 546.1272. Found, %: C 66.32; H 4.14; N 7.88. C29H21N3O7. Calculated, %:
C 66.54; H 4.04; N 8.03.
Thermal Reactions of Aziridines 1a and 1e with DMAD (General Method). A solution of aziridine
1a or 1e (0.5 mmol) and DMAD (213 mg, 1.5 mmol) in anhydrous toluene (10 ml) was heated in a thick-walled
glass reactor. The solvent was then distilled off and the residue was separated on a column packed with 20 g
silica gel.
A mixture of DMAD and aziridine 1a was heated for 5 h at 150°C. The reaction mixture was evaporated
and the residue was separated by column chromatography eluting with from 6:1 to 1:1 hexane–ethyl acetate. The
fraction containing adduct 5a was again separated on a column packed with 10 g silica gel, eluting with
dichloromethane to give 53 mg (35%) pyrrole 5a and 11 mg (14%) oxazole 3a.
Dimethyl Ester of 2-Acetyl-5-phenyl-1H-pyrrole-3,4-dicarboxylic Acid (5a) was obtained as colorless
1
crystals, mp 107°C. H NMR spectrum, , ppm: 2.45 (3H, s, CH3); 3.74 (3H, s, OCH3); 3.99 (3H, s, OCH3);
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7.43-7.46 (3H, m, H-p, H-m); 7.54-7.57 (2H, m, H-o); 9.47 (1H, br. s, NH). C NMR spectrum, , ppm: 26.78
180