920
Sedlak, Halama, Kavalek, Machacek, Mitas, Sterba:
Bis-4,4′-(5-methyl-5-isopropyl-4-imidazolinon-2-yl)azoxybenzene (3a)
2-(4-Nitrobenzoylamino)-2,3-dimethylbutanamide(1a; 2 g, 8 mmol), methanol (20 ml), and 5 M sodium
methoxide (1 ml) were placed in a 50 ml flask equipped with a reflux condenser, and the mixture
was refluxed 8 h, whereupon the solvent was distilled off until dry from a water bath. The residue
was neutralized with methanolic hydrogen chloride, and the substance obtained was collected by suc-
tion, washed with water and with acetone. After drying, the product was reprecipitated from di-
methylformamide with water to give 1 g (29%) yellow microcrystalline compound 3a, m.p. 312 °C
(dec.). 1H NMR spectrum ((CD3)2SO–TFA): 11.70 brs, 1 H (NH); 11.59 brs, 1 H (NH); 8.58 and
8.45 AA′XX′, 2 × 2 H (arom.); 8.48 and 8.31 AA′XX′, 2 × 2 H (arom.); 2.19 sept, 1 H (CH(CH3)2);
2.11 sept, 1 H (CH(CH3)2); 1.56 s, 3 H (CCH3); 1.46 s, 3 H (CCH3); 1.11 d, 3 H, J = 6.99
(CH(CH3)); 1.09 d, 3 H, J = 6.94 (CH(CH3)); 0.97 d, 3 H, J = 6.79 (CH(CH3)); 0.91 d, 3 H, J = 6.76
(CH(CH3)). 13C NMR spectrum ((CD3)2SO–TFA): 182.32 and 180.26 (CO), 166.28 and 164.92 (C-2,2′),
151.23 and 148.90 (C-9,9′), 130.71 and 130.48 (C-7,7′), 127.82 and 122.59 (C-6,6′), 125.60 and
123.57 (C-8,8′), 71.84 and 70.95 (C-5,5′), 32.02 and 34.88 (CH(CH3)2), 19.69 and 19.38 (CCH3),
16.62, 16.50, 16.44, and 16.33 (CH(CH3)2).
Bis-4,4′-(5,5-dimethyl-4-imidazolinon-2-yl)azoxybenzene (3b)
Compound 3b was prepared from compound 1c in the same way as compound 3a, yield 45%, m.p.
1
300 °C (dec.). H NMR spectrum ((CD3)2SO–TFA): 11.65 brs, 1 H (NH); 11.55 brs, 1 H (NH); 8.46
and 8.26 AA′XX′, 2 × 2 H (arom); 8.23 and 8.19 AA′BB′, 2 × 2 H (arom.); 1.37 s, 6 H (C(CH3)2);
1.36 s, 6 H (C(CH3)2). 13C NMR spectrum ((CD3)2SO–TFA): 181.38 and 180.28 (CO), 165.33 and
164.64 (C-2,2′), 151.51 and 148.86 (C-9,9′), 130.71 and 130.65 (C-7,7′), 127.18 and 122.72 (C-6,6′),
125.70 and 123.70 (C-8,8′), 65.04 and 64.31 (C-5,5′), 22.93 and 22.86 (CH3).
The authors are indebted to Dr Miroslav Ludwig from Department of Organic Chemistry, University
of Pardubice, for carrying out the titration determination of pKA. The research was supported by the
Grant Agency of the Czech Republic (Grant No. 203/94/0123).
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Collect. Czech. Chem. Commun. (Vol. 61) (1996)