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Reactions of Quinazoline Alkaloids and their Derivatives with Electrophilic Reagents
Authors:Z U Samarov  Z M Khakimova  R Okmanov  B Tashkhodzhaev  Kh M Shakhidoyatov
Institution:(1) S. Yu. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan
Abstract: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. UDC 547.944/945 547.856.1 Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 387-393, July-August, 2008. Original article submitted May 5, 2008.
Keywords:deoxypeganine  deoxyvasicinone  2-3-tetramethylene-  2-3-pentamethylene-3  4-dihydroquinazol-4-ones  1  2  3  4-tetrahydro-2  3-polymethylenequinazol-4-ones  isocyanates  electrophilic substitution  alkaloids  x-ray diffraction analysis  carbamoylation  acylation
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