A visible‐light‐promoted strategy for the decarboxylative C‐3 carbamoylation of quinoxalinone scaffolds is developed. This approach initiates through the formation of an EDA complex between oxamic acid and quinoxalinone. Successive SET and decarboxylative carbamoylation construct the C‒C bond. This method utilizes aerial oxygen as the green oxidant and eradicates the process from the use of external photocatalysts and transition metals. Detailed synthetic and photophysical studies enlighten the reaction pathway.
Synthesis and Quantitative Structure−Activity Relationships of Oxanilates as Chemical Hybridizing Agents for Wheat (Triticum aestivum L.)
摘要:
Chemical hybridizing agents (CHAs) can facilitate two-line breeding in heterosis programs of crops. Twenty-seven oxanilates having different aromatic substitutions were synthesized and screened as CHAs on two genotypes of wheat, PBW 343 and HID 2733, during two Rabi (winter) seasons, 200001 and 2001-02. The oxanilates prepared by thermal condensation of anilines with diethyl oxalate or by acylation with ethoxycarbonyl methanoyl chloride were sprayed at 1000 and 1500 ppm at the premeiotic stage of wheat, when the length of the emerging spike of the first node was 7-8 mm. Pollen sterility and spikelet sterility were measured in each treatment. Ethyl oxanilates 5, 6, and 25, containing 4-F, 4-Br, and 4-CF3 aromatic substituents, respectively, induced greater than 98% spikelet sterility, the desired level, at 1500 ppm. Quantitative structure -activity relationship analysis revealed a direct relationship between F-p and molecular mass but an inverse relationship between MR, E-S, and R in influencing the bioactivity. Several F-1 hybrids were developed using 5, and at least one showed heterosis.
Novel compounds, their salts and compositions related thereto having activity against mammalian factor Xa are disclosed. The compounds are useful in vitro or in vivo for preventing or treating coagulation disorders.
Chemical Hybridizing Agents for Chickpea (<i>Cicer arietinum</i> L.): Leads from QSAR Analysis of Ethyl Oxanilates and Pyridones
作者:Kajal Chakraborty、C. Devakumar
DOI:10.1021/jf052435h
日期:2006.3.1
In the self-pollinated crops such as chickpea, induction of male sterility by deployment of chemical hybridizing agents (CHAs) facilitating "two-line" approach holds immense potential in heterosis breeding. A total of 40 test CHAs comprising 20 ethyl oxanilates and 20 pyridones were screened as potential CHAs on chickpea (variety BG 1088) at 500, 800, and 1000 ppm. Three test compounds mostly having either F (4)/Br (5)/CF3 (19) at the para position of the aryl ring from a pool of 20 ethyl oxanilates were identified as the most potent CHAs causing >= 99% induction of pollen sterility and > 90% total flower sterility at 1000-ppm test concentration. Among pyridone derivatives, N-(4-chlorophenyl)-5-carbethoxy-4,6-dimethyl, 1, 2-dihydropyrid-2-one (26) was found to be the most active. Quantitative structure activity relationship (QSAR) analysis has revealed a direct involvement of Swain-Lupton field constant, F, with the target bioactivity which implied that field rather than resonance effect (R) had a positive effect on the activity. The real guiding principle for selectivity was found out to be the hydrophobic parameter pi value. The QSAR models indicated that increased steric bulk at the 4-position on the phenyl ring is associated with enhanced activity. The CHAs appeared to act by mimicking UDP-glucose, the key substrate in the synthesis of callose, or lead to an imbalance in acid-base equilibrium in pollen mother cells resulting in dissolution of callose wall by premature callase secretion.