The cationic ruthenium hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4- has been found to be an effective catalyst for the oxidative C-H coupling reaction of phenols with aldehydes to give 2-acylphenol compounds. The coupling of phenols with α,β-unsaturated aldehydes selectively gives the flavene derivatives. The catalytic method mediates direct oxidative C-H coupling of phenol and aldehyde substrate...

We have developed a novel oxidant-free direct cross-coupling reaction of 2,6-lutidine and internal alkynes leading to five-membered carbocyclic compounds mediated by nonmetallocene cationic hafnium alkyl complexes. Mechanistic studies of the coupling reaction showed that the reaction begins with C(sp(3))-H bond activation via σ-bond metathesis, after which the coordinatively unsaturated hafnium...

An efficient synthesis of chromenylphenylpropanone derivatives as warfarine-like analogues was developed by the Michael addition of 4-hydroxycoumarin to α,β-unsaturated compounds in the presence of polyvinylpolypyrrolidone supported antimony(III) chloride (PVPP-SbCl3) as a new polymeric Lewis acid catalyst in chloroform at reflux conditions without formation of 2,4-...

Cyclodextrins (CDs) are a family of cyclic oligosaccharides which are composed of α (1,4) -linked glucopyranose subunits. Thebest-characterized forms are α, β and γ CD which are consisted of six, seven and eight D-glucose units, respectively. Cyclodextrins are produced from starch by enzymatic degradation. These macrocyclic carbohydrates with polar internal cavities can form complexes with and ...

Title Stereocontrolled synthesis of carbocyclic compounds with a quaternary carbon atom based on SN2 ' alkylation of γ,δ-epoxy-α,β-unsaturated ketones Author(s) Yoshimura, Fumihiko; Kowata, Ayano; Tanino, Keiji Citation Organic & Biomolecular Chemistry, 10(28): 5431-5442 Issue Date 2012-07-28 Doc URL http://hdl.handle.net/2115/52793 Right Org. Biomol. Chem., 2012,10, 5431-5442 Reproduced by per...

A remarkable α-effect of silicon has been discovered that results in soft nucleophilicity at the Cγ of 3,3-bis(silyl) allyloxy lithium 1. The addition of 1 to α,β-unsaturated carbonyl compounds, including enals, proceeds in a 1,4- over 1,2-manner with medium to good regioselectivity, whereas the parent allyloxy lithium 4 undergoes complete 1,2-addition. The results from DFT calculations of HMPA...

In search for new natural products, which may lead to the development of new drugs for all kind of applications, novel methods are needed. Here we describe the identification of electrophilic natural products in crude extracts via their reactivity against azide as a nucleophile followed by their subsequent enrichment using a cleavable azide-reactive resin (CARR). Using this approach, natural pr...

A novel selective and substrate-dependent synthetic protocol has been developed towards the synthesis of various fluorine-containing, highly functionalized cycloalkane derivatives. The method involves the stereoselective epoxidation of some unsaturated cyclic β-amino acid derivatives as model compounds, followed by a regioselective fluoride opening of oxiranes under various conditions with Deox...

The synthesis of either monoor bis-adducts via Michael reaction between active methylene compounds and α,β-unsaturated reagents is reported. These processes are catalyzed by two heterogeneous basic catalysts, namely KG-NEt2 and KG-TBD. Both catalysts show good catalytic efficiency and can be reused several times fully preserving their efficiency. The process could be efficiently performed under...

A novel, simple, and efficient method for the synthesis of 4,5-dihydropyrazole derivatives has been developed. The reaction proceeded through the base-induced isomerization of easily accessible propargyl alcohols followed by cyclization of α,β-unsaturated hydrazones. Furthermore, selected compounds 3ab and 3ac exhibited good activities against Bel-7404 (human hepatoma cancer), HepG2 (human live...