Reactions of Quinazoline Alkaloids and their Derivatives with Electrophilic Reagents

• Published in: Chemistry of natural compounds Vol. 44; no. 4; pp. 480 - 488
• Main Authors: Samarov, Z. U, Khakimova, Z. M, Okmanov, R, Tashkhodzhaev, B, Shakhidoyatov, Kh. M
• Format: Journal Article
• Language: English
• Published: Boston Boston : Springer US 01.07.2008; Springer US; Springer Nature
• Subjects: alkaloids; benzene; bromination; chemical structure; Chemistry; Chemistry, Medicinal; Chemistry, Organic; chlorides; Life Sciences & Biomedicine; Medicine; Organic Chemistry; oxidation; Pharmacology & Pharmacy; Pharmacy; Physical Sciences; Plant Sciences; Science & Technology; x-ray diffraction analysis; 3-polymethylenequinazol-4-ones; deoxyvasicinone; alkaloids; deoxypeganine; 4-dihydroquinazol-4-ones; acylation; electrophilic substitution; 2-3-tetramethylene; isocyanates; 1,2,3,4-tetrahydro-2; carbamoylation; 2-3-pentamethylene-3; 4-tetrahydro-2; 1; 2; 3
• ISSN: 0009-3130; 1573-8388
• DOI: 10.1007/s10600-008-9106-z

Nitration of deoxypeganine (DOP), deoxyvasicinone (DOV), 2,3-tetramethylene-, 2,3-pentamethylene-, and 3,4-dihydroquinazol-4-ones and their 1,2-dihydro derivatives was studied. It was shown that the reaction pathway changed depending on the presence of a carbonyl on C-4 and an N=C bond in these compounds. Only the H atom on C-6 was subject to nitration if both functional groups were present, for example DOV and its homologs. Substitution of the H atom of either the 6-position (DOP, 1,2-dihydro-DOV, and their homologs) or the 6- and 8-positions simultaneously (DOP and its homologs) was enhanced if one of these functional groups was missing depending on the substrate:nitrating agent ratio. The bromination and nitration reactions of 1,2-dihydro-DOV and its analogs in a 1:2 ratio were accompanied by oxidation of the N¹H-CH bond with formation of 6,8-dibromo- and 6,8-nitro-DOV and their homologs. The difference in the behavior of these compounds was due to the different nucleophilicity of the benzene rings in them. The reaction of 1,2-dihydro-DOV and its homologs with isocyanates and p-nitro- and p-methylbenzoic acid chlorides was studied. 6-Nitro- and 6,8-dinitro-DOP and 6,8-dibromo- and 6,8-dinitro-DOV and their homologs and 6-bromo- and 6-nitro-1,2,3,4-tetrahydro-2,3-polymethylenequinazol-4-ones and their 1-alkyl(aryl)-carbamoyl and p-nitro(methyl)-benzoyl derivatives were synthesized. The molecular structures of 1-ethyl-and 1-(o-chlorophenyl)-carbamoyl-1,2-dihydrodeoxyvasicinones and 6,8-dinitro-2,3pentamethylene-3,4-dihydroquinazol-4-one were established.