Substituent effects of cis-cinnamic acid analogues as plant growh inhibitors
摘要:
1-O-cis-Cinnamoyl-beta-D-glucopyranose is one of the most potent allelochemicals that has been isolated from Spiraea thunbergii Sieb by Hiradate et al. It derives its strong inhibitory activity from cis-cinnamic acid (cis-CA), which is crucial for phytotoxicity. By preparing and assaying a series of cis-CA analogues, it was previously found that the key features of cis-CA for lettuce root growth inhibition are a phenyl ring, cis-configuration of the alkene moiety, and carboxylic acid. On the basis of a structure-activity relationship study, the substituent effects on the aromatic ring of cis-CA were examined by systematic synthesis and the lettuce root growth inhibition assay of a series of cis-CA analogues having substituents on the aromatic ring. While ortho- and para-substituted analogues exhibited low potency in most cases, meta-substitution was not critical for potency, and analogues having a hydrophobic and sterically small substituent were more likely to be potent. Finally, several cis-CA analogues were found to be more potent root growth inhibitors than cis-CA. (C) 2013 Elsevier Ltd. All rights reserved.
Rh(III)-Catalyzed Enaminone-Directed C–H Coupling with α-Diazo-α-phosphonoacetate for Reactivity Discovery: Fluoride-Mediated Dephosphonation for C–C Coupling Reactions
Rh(III)-catalyzed enaminone-directed C–H coupling with α-diazo-α-phosphonoacetate has been used for the identification of fluoride-mediated dephosphonation C–C coupling reactivity for the synthesis of 4-hydroxy-1-naphthoates. Intermolecular C–C coupling of α-phosphonoacetate and benzaldehyde for (E)-selective α,β-unsaturated ester synthesis has also been achieved.
treated with potassium t-butoxide in dimethyl sulphoxide the chromium tricarbonyl complex of 3-(2-fluorophenyl)propan-1-ol underwent a rapid intramolecular nucleophilic substitution to give the corresponding complex of chroman, from which the heterocycle was obtained by oxidation with iodine. With metal alkoxides the chromium tricarbonyl complex of 2-(2-fluorophenyl)ethanol gave either mixtures (from which
Merging Grubbs second-generation catalyst with photocatalysis enables<i>Z</i>-selective metathesis of olefins: scope, limitations, and mechanism
作者:Saïf Eddine Chérif、Avisek Ghosh、Saloua Chelli、Isabelle M. Dixon、Jamil Kraiem、Sami Lakhdar
DOI:10.1039/d2sc03961c
日期:——
Olefin cross-metathesis is a cornerstone reaction in organic synthesis where stereoselectivity is typically governed by the structure of the catalyst. In this work, we show that merging Grubbs second generation catalyst, a classical E-selective catalyst, with a readily available photocatalyst, enables the exclusive formation of the contra-thermodynamic Z-isomer. The scope and limitations of this unprecedented