Syntheses Based on Triacanthine
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SYNTHESES BASED ON TRIACANTHINE
Sh. B. Rakhimov* and V. I. Vinogradova
N-containing heterocycles occupy a special place in heterocyclic chemistry because of their enormous structural variety and their presence in biologically active compounds. The subject of our research was the available alkaloid triacanthine, which is produced by plants of the genus Gleditsia. Triacanthine (1) has been used in medicine for stomach ulcers, spastic colitis, bronchial asthma, and hypertonic disease stages I and II [1]. The raw material for producing 1 was young leaves of G. triacanthos L. (Leguminosae). The triacanthine contents drops sharply as leaves age. Young leaves contain up to 1% of the alkaloid triacanthine; flowers, 0.3%; other organs, insignificant amounts [2], including pods of G. triacanthos and G. sinensis, ~0.01% of total alkaloids. The period of high triacanthine content is short. Therefore, young leaves of G. triacanthos collected at the start of vegetation were used as the main raw material to obtain triacanthine. The literature contains data for the production of only dihydro- and N-benzyltriacanthine and triacanthine methyl iodide although 1 was isolated over 50 years ago and contains a primary amine [3]. Therefore, the ability to produce other derivatives seemed of definite interest. R
NH2
HN N
N
a, b, c N
N
N
N
9
3
N
N
t°
CH2 CH
10 CH 2
C
12
H3C
1
CH
CH3 1
C
H 3C
CH3
2-4
2: R = COCH3; 3: R = CH2CH2OH; 4: R = CH2OH a. (CH2CO)2O; b. HOCH2CH2Cl; c. CH2O
Acylation of 1 by acetic anhydride formed N-acetyltriacanthine (2) in 41.6% yield. The reaction was performed in acetic anhydride without a solvent and with heating for 2 h. N-Hydroxyethyltriacanthine was initially produced by the reaction of 1 with ethylene chlorohydrin in EtOH in the presence of Na2CO3 using a 1:1 mole ratio [4]. However, we performed the reaction in ethylene chlorohydrin because it practically did not occur under the above conditions. Use of it as the reagent and solvent produced the mono-N-alkylated derivative 3 in 55% yield. A dimer of triacanthine with an >N–CH2–N< linker was produced by reacting 1 with formaldehyde in EtOH by the literature method [5, 6]. Spectral data showed that 3-(3-methylbut-2-enyl)-3H-purin-6-ylamino)methanol (4) formed in 65% yield instead of the expected dimer. The synthesized compounds were crystalline and very soluble in MeOH, EtOH, and CHCl3 (except 3). The C10 protons in PMR spectra of 2, 3, and 4 appeared as a doublet at δ 5.07, 5.08, and 4.96 ppm, respectively. The N-acetyl group of 2 resonated as a singlet at δ 2.44; the methylene protons of 3, at δ 4.62 and 3.93 ppm; the N-hydroxymethyl group of 4, as a broad singlet at δ 4.96 ppm. S. Yu. Yunusov Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, 100170 Tashkent, e-mail: [email protected], Translated from Khimiya Prirodnykh Soedinenii, No. 5, September–October, 2020, pp. 820–821. Original article submitted December 28, 2017. 960
0009-3130/20/5605-0960
©2020
Springer Science+Business
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