18120-64-4Relevant articles and documents
Dual Activity of Grubbs-Type Catalyst in the Transvinylation of Carboxylic Acids and Ring-Closing Metathesis Reactions
Brodzka, Anna,Koszelewski, Dominik,Ostaszewski, Ryszard,Brodzka, Anna,Ostaszewski, Ryszard
, p. 15305 - 15313 (2020/12/01)
The development of a multifunctional catalyst, which mimics the promiscuity of enzymes, that would catalyze more than one chemical transformation in a single reaction vessel is one of the key points of modern sustainable chemistry. The results of our experiments indicated that Grubbs-type catalysts possess such multitask activity, catalyzing the transvinylation reaction of carboxylic acids without losing their original metathetic activity. This new activity of Grubbs catalysts was evidenced on several examples. It allows us to design a transvinylation/ring-closing metathesis (RCM) cascade reaction leading to the formation of endocyclic enol lactones from unsaturated carboxylic acids in an one-pot procedure. This unique ability of Grubbs catalyst to catalyze multiple mechanically distinct cascade reactions in a chemoselective way offers the new possibility for the synthesis of complex compounds from simple, easily accessible substrates.
Evaluating aryl esters as bench-stable C(1)-ammonium enolate precursors in catalytic, enantioselective Michael addition-lactonisations
Young, Claire M.,Taylor, James E.,Smith, Andrew D.
supporting information, p. 4747 - 4752 (2019/05/24)
An evaluation of a range of aryl, alkyl and vinyl esters as prospective C(1)-ammonium enolate precursors in enantioselective Michael addition-lactonisation processes with (E)-trifluoromethylenones using isothiourea catalysis is reported. Electron deficient aryl esters are required for reactivity, with 2,4,6-trichlorophenyl esters providing optimal product yields. Catalyst screening showed that tetramisole was the most effective isothiourea catalyst, giving the desired dihydropyranone product in excellent yield and stereoselectivity (up to 90 : 10 dr and 98 : 2 er). The scope and limitations of this process have been evaluated, with a range of diester products being generated after ring-opening with MeOH to give stereodefined dihydropyranones with excellent stereocontrol (10 examples, typically ～90 : 10 dr and >95 : 5 er).
Regio- and Stereoselective Chan-Lam-Evans Enol Esterification of Carboxylic Acids with Alkenylboroxines
Steemers, Luuk,Wijsman, Linda,van Maarseveen, Jan H.
supporting information, p. 4241 - 4245 (2018/10/02)
Efficient and scalable Cu(II)-mediated enol esterification methodology of carboxylic acids from alkenyl boroxines and boronic acids is presented. The reaction shows a wide scope in aliphatic and aromatic carboxylic acids in combination with several alkenyl boroxines. In the case of 2-substituted alkenyl boroxines the double bond configuration was fully retained in the enol ester product. Also N-hydroxyimides and imides could be transformed in the respective amidooxy vinyl enol ethers and vinyl enamides. Finally, with the exception of methionine, all other 19 canonical amino acids showed their compatibility to give the enol esters in a stereoselective fashion. (Figure presented.).
Enzymatic synthesis of new C-6-acylated derivatives of NAG-thiazoline and evaluation of their inhibitor activities towards fungal β-N- acetylhexosaminidase
Krejzova, Jana,Simon, Petr,Vavrikova, Eva,Slamova, Kristyna,Pelantova, Helena,Riva, Sergio,Spiwok, Vojtech,Kren, Vladimir
, p. 128 - 134 (2013/03/13)
β-N-Acetylhexosaminidases (EC 3.2.1.52) from the CAZy glycoside hydrolase families 20 and 84 are two distinct enzyme groups with similar reactivity and different physiological functions, thus selective inhibition of these enzymes is of crucial importance.
Substituent Effects on the Intramolecular Photochemical Reactions of Phenyl-Ethenyl Non-conjugated Bichromophoric Systems
Ellis-Davies, Graham C. R.,Gilbert, Andrew,Heath, Peter,Lane, Jon C.,Warrington, John V.,Westover, David L.
, p. 1833 - 1842 (2007/10/02)
The effects of substitution on the photochemistry of phenyl-ethenyl bichromophoric systems are reported.Methyl substitution at the 2-, 3-, 5-, and 1,1,2-positions in the pentene moiety of 5-phenylpent-1-ene reduces both reaction efficiency and selectivity but in contrast to intramolecular analogues the photoreaction of 3-phenethylcyclohexene is comparable with that of the corresponding cyclopentene.Incorporation of ester units in the connecting unit between the chromophores or on the ethene inhibits intramolecular cyclisation as does the presence of para OMe, CN, or COMe groups in 5-phenylpent-1-ene.In contrast reaction selectivity and efficiency are greatly promoted by ortho Me or OMe groups and the products reflect exlusive 1,3-cycloaddition.The presence of a para Me group in 5-phenylpent-1-ene leads to specific 2,6-intramolecular cyclisation but the reaction of the meta-Me derivative leads to four products derived from 1,3- and 1,5-intramolecular cycloaddition.The observations are discussed in terms of mechanisms of arene-ethene photoreactions and preferred conformations of the bichromophores.
