Simple and Convenient Preparation of New Highly Protected Aziridines Fused with Pyrroline Rings

Abstract

New highly protected aziridines fused with pyrroline rings are obtained in satisfactory yields by reaction of 1,2-diaza-1,3-butadienes with methyl 2-benzoylamino-3-dimethylamino-propenoate in toluene under reflux.

Key words

Michael additions - regioselectivity - bicyclic compounds - 1,2-diaza-1,3-butadienes - aziridines

References

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• 2b

  Attanasi, O. A.; De Crescentini, L.; Favi, G.; Filippone, P.; Giorgi, G.; Mantellini, F.; Santeusanio, S. J. Org. Chem., in press.

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5

A representative procedure for the preparation is as follows:
Preparation of Dimethyl 2-[(methoxycarbonyl)amino]-6-benzoyl-3-methyl-2,6-diazabicyclo [3.1.0] hex-3-ene-4,5-dicarboxylate 3a. 1,2-Diaza-1,3-butadiene 1a (1 mmol) and methyl 2-benzoylamino-3-dimethylamino-propenoate 2 (1 mmol) were dissolved in 30 mL of toluene and refluxed until the reaction was complete (monitored by TLC). The reaction mixture was concentrated directly under reduced pressure and product 3a was isolated by chromatography on silica, eluting with cycloexane-ethyl acetate (70:30) and then purified by crystallization from diethyl ether.
3a: mp 106-110 °C; IR(nujol) 3287, 2765, 1704, 1658
cm^-1; ¹H NMR (DMSO-d ₆) δ 2.07 (s, 3 H, CH₃), 3.60 (s, 3 H, OCH₃), 3.66 (s, 3 H, OCH₃), 6.17 (s, 1 H, CH), 7.45-7.91 (m, 5 H_ar), 9.94 (b.s., 1 H, NH); ¹³C NMR (DMSO-d ₆) δ 11.3 (CH₃), 50.6 (OCH₃), 52.5 (OCH₃), 83.8 (C5), 98.2 (C1), 100.7 (C4), 126.0 (C_ar), 128.1 (C_ar), 128.5 (C_ar), 132.1 (C_ar), 156.0 (C3), 161.5 (CO), 163.3 (CO), 163.8 (CO), 169.4 (CO) MS m/z 389 (M⁺, 76), 360(32), 330(88), 254(32), 222(35), 167(100). Anal.Calcd for C₁₈H₁₉N₃O₇: C, 55.53; H, 4.92; N, 10.79. Found: C, 55.45; H, 4.98; N, 10.66.