Síntese de novas fitotoxinas derivadas do 8-oxabiciclo[3.2.1]oct-6-en-3-ona

Abstract

Recebido em 27/4/04; aceito em 22/9/04; publicado na web em 2/2/05 SYNTHESIS OF NEW PHYTOTOXINS DERIVED FROM 8-OXABICYCLO[3.2.1]OCT-6-EN-3-ONE. The [4+3] cycloaddition was utilized in order to prepare 8-oxabicyclo[3.2.1]oct-6-en-3-one (1) derivatives. The correspondent acetonide 6 was converted into several alcohols (11-16). Addition of aryllithium reagents to 6 resulted in 3-(2-fluorophenyl)-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3α-ol (11, 72%) and 3-(2,4-dimethoxyphenyl)-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3α-ol (16, 20%). The 3-butyl-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3α-ol (15, 56%) was obtained through a Grignard reaction. Reduction of 6 resulted in 6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3β-ol (7, 62%) and 6,7-exoisopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3α-ol (8, 20%). The alcohols were treated with thionyl chloride in pyridine, and the corresponding alkenes were obtained with 31-80% yield. The effect of these compounds on the development of radicle and aerial parts of Sorghum bicolor was evaluated.

Synthesis and Cytotoxic Activity of Some 3-Benzyl-5-Arylidenefuran-2(5H)-ones

“…As part of our ongoing efforts to develop bioactive compounds [21][22][23][24][25], and taking into consideration that there is no systematic investigation regarding the cytotoxic activity of nostoclides analogues, we describe herein the preparation and evaluation of antitumour activity of ten new lactone analogues of the nostoclides.…”

Dalbergia brasiliensis Vogel Extracts in vitro Antioxidant Activity and Phytotoxic Effect in Lactuca sativa and Allium cepa

“…sativa and A. cepa root growth were most affected than hypocotyls and coleoptiles. Baziramakenga et al, (1995) emphasizes that, besides root contact with extracts, root tissues are more permeable to allelochemicals which may alter tissues' initial growth (Nishida et al, 2005), damaging root methabolic activities and cellular division on root extremities that might lead to dry weight reduction (Singh et al, 2003).…”

“…Growth bioessays followed Barnes et al (1987) and Macias et al (2000) described methods. After seven days of radicle protusion, root and hypocotyl/coleoptile were measured over millimiter paper (10 seedlings from each Petri dish).…”

“…Allelophaty defines plant interactions employing phytotoxins, once donor plant negatively affects target plant, providing advantage to donor plant (Dayan & Duke, 2009). Secondary metabolites are able to bring on beneficial and harmful effects, depending on some characteristics such as amount, chemical properties and present functional groups (Barbosa et al, 2005;Goldfarb et al, 2009). Also, are considered as greatly responsible for allelophatic effects observed in nature, since these compounds are important agents against natural predators and ultraviolet radiation, including simple phenolic and heteroside compounds, coumarins, xanthans, tannins, flavonoids, saponins, alkaloids and sulfur compounds (Haida et al, 2010;Jácome et al, 2004).…”

Synthesis and insecticidal activity of new phosphoramidates

“…Although they have these disadvantages, organophosphate insecticides account for more than 24% of the insecticide market and several phosphoramidates are commercially available. [5][6] To continue our e ort to develop new compounds with insecticidal 7,8) and phytotoxic activity, [9][10][11] we describe in the present investigation the synthesis of new phosphoramidates and the evaluation of their activity against Lepidoptera species that attack important commercial crops, namely Ascia monuste (Latr.) (Pieridae), Diaphania hyalinata (L.) (Crambidae) and Plutella xylostella (L.) (Plutellidae).…”