Herein, we have disclosed a catalytic asymmetric 1,5(6)-selective Michael/cyclization reaction of α-hydroxyimino cyclic ketones with γ,β-unsaturated α-keto esters. Unlike the previous catalytic strategies, this reaction provides a convenient 1,5(6)-selective asymmetric pathway to access synthetically useful ring-fused dihydropyrans. In general, high levels of yield, enantio- and diastereoselect...

Indium(III) triflate is found to be an effective catalyst for the benzannulation reactions of o-alkynylbenzaldehydes with enolisable aldehydes, ketones, 1,3-diketones and β-keto esters. The reactions produce naphthyl ketones through ring opening of adducts arising from the inverse electron demand Diels-Alder reactions between in situ generated isochromenylium cations and enols. The main feature...

SYNLETT 2006, No. 8, pp 1169–117215.05.2006 Advanced online publication: 10.03.2006 DOI: 10.1055/s-2006-932461; Art ID: W30605ST © Georg Thieme Verlag Stuttgart · New York Abstract: Various enantiomerically pure a-hydroxy esters were synthesized by asymmetric hydrogenation of a-keto esters catalyzed by Ru-Cn-Tunephos complex. Up to 97.1% ee has been achieved for both a-aryl and a-alkyl substitu...

Engineering dual-function single polypeptide catalysts with two abiotic or biotic catalytic entities (or combinations of both) supporting cascade reactions is becoming an important area enzyme engineering and catalysis. Here we present the development a PluriZyme , TR 2 E efficient native transaminase ( k cat : 69.49±1.77 min -1 ) artificial esterase 3908 to 0.41 activities, integrated into sca...

[reaction: see text] The catalytic enantioselective electrophilic fluorination promoted by quaternary ammonium salt from cinchonine as a phase-transfer catalyst is described. Treatment of beta-keto esters with N-fluorobenzenesulfonimide as the fluorine source under mild reaction conditions afforded the corresponding alpha-fluoro beta-keto esters in exellent yields with good to moderate enantiom...