Highly enantioselective synthesis of γ-substituted butenolides via the vinylogous Mukaiyama–Michael reaction catalyzed by a chiral scandium(iii)–N,N′-dioxide complex
A highly efficient catalytic asymmetric vinylogous Mukaiyama–Michael reaction of the 2-silyloxyfuran with chalcone derivatives, catalyzed by a chiralN,N′-dioxide–scandium(III) complex, has been accomplished which tolerates a wide range of substrates. The reaction proceeds with complete regioselectivities, excellent diastereoselectivities (up to >99 : 1 dr) and good to excellent enantioselectivities
The catalytic asymmetric aza-Michaelreaction of benzoyl hydrazine toward chalcones through the nonactivated amine moiety conjugated addition was facilitated by the developed N,N'-dioxide-Sc(OTf)(3) complex under mild conditions, affording the pharmacologically and synthetically useful products in moderate to high yields with up to 97% ee.
Kinetic Resolution of β-Hydroxy Carbonyl Compounds via Enantioselective Dehydration Using a Cation-Binding Catalyst: Facile Access to Enantiopure Chiral Aldols
作者:Sushovan Paladhi、In-Soo Hwang、Eun Jeong Yoo、Do Hyun Ryu、Choong Eui Song
DOI:10.1021/acs.orglett.8b00547
日期:2018.4.6
β-hydroxy carbonyl (aldol) compounds through enantioselective dehydration process was developed using a cation-binding Song’s oligoethylene glycol (oligoEG) catalyst with potassium fluoride (KF) as base. A wide range of racemic aldols was resolved with extremely high selectivity factors (s = up to 2393) under mild reaction conditions. This protocol is easily scalable. It provides an alternative approach for
Access to 2‐Amino‐3‐Arylthiophenes by Base‐Catalyzed Redox Condensation Reaction Between Arylacetonitriles, Chalcones, and Elemental Sulfur
作者:Thi Thu Tram Nguyen、Van Anh Le、Pascal Retailleau、Thanh Binh Nguyen
DOI:10.1002/adsc.201901235
日期:2020.1.7
three‐component reaction of arylacetonitriles, chalcones and elemental sulfur. The first step consists of a DBU‐catalyzed formation of Michael adduct between arylacetonitriles and chalcones. The second step is a cascade of DABCO‐catalyzed sulfuration of the Michael adduct with elemental sulfur followed by an oxidative cyclization to afford thiophenes. Compared to the Gewald reactions and related transformations
The first catalyticasymmetric dynamic resolution of unprotected racemic 3-(4-alkylcyclohexylidene)indolin-2-ones via one step directvinylogousMichael reaction with chalcones was realized by a chiral N,N′-dioxide/Sc(III) complex catalytic system. A variety of (Z)-4-alkyl-2-((3-oxo-1,3-diarylpropyl)cyclohexylidene)-indolin-2-ones with three stereogeniccenters at ξ-, γ- and δ’-positions were obtained