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.
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.
Amides as precursors of imidoyl radicals in cyclisation reactions
作者:W. Russell Bowman、Anthony J. Fletcher、Jan M. Pedersen、Peter J. Lovell、Mark R.J. Elsegood、Elena Hernández López、Vickie McKee、Graeme B.S. Potts
DOI:10.1016/j.tet.2006.10.030
日期:2007.1
Amides have been successfully used as precursors of imidoyl radicals for radical cyclisation. The amides have been converted to imidoyl selanides via reaction with phosgene to yield imidoyl chlorides followed by reaction with potassium phenylselanide. Imidoyl selanides were reacted with tributyltin hydride (Bu3SnH) as the radical mediator with triethylborane or AIBN as initiators to yield imidoyl radicals
The One-Pot Wittig Reaction: A Facile Synthesis of α,β-Unsaturated Esters and Nitriles by Using Nanocrystalline Magnesium Oxide
作者:Boyapati M. Choudary、Koosam Mahendar、M. Lakshmi Kantam、Kalluri V. S. Ranganath、Taimur Athar
DOI:10.1002/adsc.200606001
日期:2006.9
Nanocrystalline magnesium oxide was found to be an effective heterogeneous, solid base catalyst for the one-pot Wittig reaction to afford α,β-unsaturatedesters and nitriles in excellent yields with high E-stereoselectivity in the presence of triphenylphosphine under mild conditions.
Stereoselective Synthesis of Polysubstituted Alkenes through a Phosphine-Mediated Three-Component System of Aldehydes, α-Halo Carbonyl Compounds, and Terminal Alkenes
作者:Da-Neng Liu、Shi-Kai Tian
DOI:10.1002/chem.200900177
日期:2009.4.27
mediate the one‐pot Wittig reaction of aldehydes with α‐halo carbonylcompounds for the synthesis of 1,2‐disubstituted and trisubstituted alkenes in an excellent stereoselective fashion. Furthermore, the first one‐pot, three‐component reaction of aldehydes, α‐halo acetates, and terminalalkenes has been developed in the presence of PPh3 to produce trisubstituted alkenes with excellent E selectivity (see
Iron hydride complexes of the general formula P2Fe(NO)CO)H are highly active catalysts for the hydrosilylation of aldehydes or ketones and phosphine oxides. Depending on the solvent, the in situ reduction of the phosphine oxide can be faster than the corresponding hydrosilylation of a carbonyl group. This unusual activity was used within the context of catalytic Wittig olefination.
Regio- and diastereoselective Pd-catalyzed aminochlorocyclization of allylic carbamates: scope, derivatization, and mechanism
作者:Bruna Papa Spadafora、Francisco Wanderson Moreira Ribeiro、Jullyane Emi Matsushima、Elaine Miho Ariga、Isaac Omari、Priscila Machado Arruda Soares、Diogo de Oliveira-Silva、Elisângela Vinhato、J. Scott McIndoe、Thiago Carita Correra、Alessandro Rodrigues
DOI:10.1039/d1ob00670c
日期:——
diastereoselective synthesis of oxazolidinones via a Pd-catalyzed vicinal C–N/C–Cl bond-forming reaction from internal alkenes of allylic carbamates is reported. The oxazolidinones are obtained in yields of 44 to 95% with high to excellent diastereoselectivities (from 6 : 1 to >20 : 1 dr) from readily available precursors. This process is scalable, and the products are suitable for the synthesis of useful amino