title: Synthesis of new phytogrowth-inhibitory substituted aryl-p-benzoquinones.
abstract: Reaction of [(2-alkyloxy)methyl]-1,4-dimethoxybenzene 10 (alkyl=butyl, hexyl, decyl, tridecyl, tetradecyl, hexadecyl, and octadecyl) with ceric ammonium nitrate in order to produce p-benzoquinones (=cyclohexa-2,5-diene-1,4-diones) afforded 5-[(alkyloxy)methyl]-2-(4-formyl-2,5-dimethoxyphenyl)benzo-1,4-quinones 12a-12g in yields that varied from 46 to 97%, accompanied by 2-[(alkyloxy)methyl]benzo-1,4-quinones 11a-11g in only small quantities (< or =5%). These quinones resemble the natural phytotoxic compound sorgoleone, found in Sorghum bicolor. This reaction exemplifies a general procedure for the synthesis of novel aryl-substituted p-benzoquinones. The selective effects of compounds 12a-12g, at the concentration of 5.5 ppm, on the growth of Cucumis sativus, Sorghum bicolor, Euphorbia heterophylla, and Ipomoea grandifolia were evaluated. All compounds caused some inhibition upon the aerial parts and root growth of the tested plants. The most active compound, 2-(4-formyl-2,5-dimethoxyphenyl)-5-[(tridecyloxy)methyl]-benzo-1,4-quinone (12d), caused between 3 and 18%, and 12 and 29% inhibition on the roots and aerial parts development of Cucumis sativus and Sorghum bicolor, respectively, and between 77 and 85%, and 34 and 52% inhibition on the roots and aerial parts growth of Euphorbia heterophylla and Ipomoea grandifolia, respectively.
authors.affiliation: Departamento de Química, Universidade Federal de Viçosa, 36571-000, Viçosa--MG, Brazil. lcab@ufv.br <lcab@ufv.br>
authors.forename: Luiz Cláudio
authors.initials: LC
authors.lastname: de Almeida Barbosa
authors.forename: Elson Santiago
authors.initials: ES
authors.lastname: de Alvarenga
authors.forename: Antônio Jacinto
authors.initials: AJ
authors.lastname: Demuner
authors.forename: Luciano Sindra
authors.initials: LS
authors.lastname: Virtuoso
authors.forename: Antônio Alberto
authors.initials: AA
authors.lastname: Silva
mesh_terms: D016227:Benzoquinones / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D001592:Benzyl Alcohols / Q000737:chemistry; D018553:Cucumis sativus / Q000187:drug effects / Q000254:growth & development; D028481:Euphorbia / Q000187:drug effects / Q000254:growth & development; D027741:Ipomoea / Q000187:drug effects / Q000254:growth & development; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development*; D045868:Sorghum / Q000187:drug effects / Q000254:growth & development
chemical_list: D016227:Benzoquinones; D001592:Benzyl Alcohols; C004532:quinone