132797-26-3Relevant academic research and scientific papers
An approach to catalytic enantioselective protonation of prochiral lithium enolates
Riviere, Pierre,Koga, Kenji
, p. 7589 - 7592 (1997)
Protonation of prochiral lithium enolates (4), prepared from racemic 2-substituted-1- tetralones (2) via their silyl enol ethers (3), with excess succinimide in the presence of lithium bromide and 0.2 equivalent of a chiral tetradentate amine ((R)-1) in toluene at -78°C gave optically active 2 in up to 83% ee.
Enantioselective Protonation of Achiral Lithium Enolates Using a Chiral Amine in the Presence of Lithium Bromide
Yasukata, Tatsuro,Koga, Kenji
, p. 35 - 38 (1993)
Asymmetric synthesis of 2-alkyl-1-tetralones (2) was achieved in up to 91percent e.e. by enantioselective protonation of their corresponding achiral lithium enolates (4) using a chiral amine ((R)-1) as a chiral source in the presence of lithium bromide.En
Stereoselective reactions. Part 31: Catalytic asymmetric alkylation of achiral lithium enolates using a chiral tetradentate amine in the presence of an achiral bidentate amine
Imai, Mitsuko,Hagihara, Atsushi,Kawasaki, Hisashi,Manabe, Kei,Koga, Kenji
, p. 179 - 185 (2000)
Catalytic asymmetric alkylation of achiral lithium enolates of 1- tetralone and cyclohexanone with reactive alkyl halides was realized by using a combination of a chiral tetradentate amine (~0.05 equiv.) and an achiral bidentate amine (2 equiv.).
Rate enhancement with high ratio of the monoalkylated product to the dialkylated product in the alkylation of the lithium enolate of 1-tetralone with reactive alkyl halides
Goto,Akimoto,Aoki,Shindo,Koga
, p. 1529 - 1531 (2000)
The reactions of the lithium enolate of 1-tetralone with reactive alkyl halides were examined in the absence and in the presence of 3 eq of various ligands for the lithium. It is shown that the rates of the reactions are enhanced greatly in the presence a tetradentate amine (1,1,4,7,10,10-hexamethyltriethylenetetramine), and the ratio of the monoalkylated product to the dialkylated product is increased under shorter reaction times.
Catalytic asymmetric protonation of achiral lithium enolates mediated by a chiral tetraamine ligand with water as a proton source
Yamashita, Yasuhiro,Emura, Yoshihiro,Odashima, Kazunori,Koga, Kenji
, p. 209 - 213 (2000)
Catalytic protonation of achiral lithium enolates (derived from 2- substituted-1-tetralones), mediated by a chiral tetraamine ligand [(R,R)- N,N'-bis[1-phenyl-2-(1-piperidinyl)ethyl]-1,3-propanediamine (0.10 equiv.)], was achieved with high enantioselecti
Why is alkylation of an enolate accompanied by so much polyalkylation?
Streitwieser, Andrew,Kim, Yeong-Joon,Wang, Daniel Ze-Rong
, p. 2599 - 2601 (2001)
(Equation presented) The lithium enolate 1-Li of 6-phenyl-α-tetralone forms a monomer-tetramer equilibrium in THF at 25 °C with K1,4 = 4.7E+10 M-3. The lithium enolate 2-Li, however, forms a monomer-dimer equilibrium with K1,2/
Regioselective reduction of the homoisoflavone system with dialkylboranes in the presence of palladium catalysts
Hoshino, Yukio,Tanaka, Hiroto,Takeno, Noboru
, p. 2923 - 2928 (1998)
(E)-3-Benzylidene-4-chromanones were regioselectively reduced to 3- benzyl-4-chromanones through the 1,4-addition of dialkylboranes, especially 9-borabicyclo[3.3.1]nonane, in excellent yields. The reaction was efficiently promoted by some palladium cataly
Highly enantiofacial protonation of prochiral lithium enolates with chiral β-hydroxy sulfoxides
Kosugi, Hiroshi,Hoshino, Kunihide,Uda, Hisashi
, p. 6861 - 6864 (1997)
Highly enantioselective protonation of prochiral lithium enolates is disclosed. The present method employed (S,R(s)) CF3-hydroxy sulfoxide (3b) as the chiral protonating agent, and the protonation or lithium enolates of cyclohexanone derivatives with 3b proceeded with high enantioselectivities.
1,1,4,7,10,10-Hexamethyltriethylenetetramine: A reagent to enhance the rate of alkylation reaction of the lithium enolate of 1-tetralone with alkyl halides
Goto, Mariko,Akimoto, Koh-ichi,Aoki, Kazumasa,Shindo, Mitsuru,Koga, Kenji
, p. 8129 - 8132 (1999)
The rate of the reaction of the lithium enolate of 1-tetralone with alkyl halides was enhanced greatly in the presence of 3 equivalents of 1,1,4,7,10,10-hexamethyltriethylenetetramine. The ratio of the monoalkylated product to the dialkylated product was found to have increased under a shorter reaction time.
Efficient asymmetric protonation of enolates with readily accessible chiral α-sulfinyl alcohols
Asensio, Gregorio,Aleman, Pedro,Cuenca, Ana,Gil, Jesus,Medio-Simon, Mercedes
, p. 4073 - 4078 (1998)
The efficient asymmetric protonation of lithium enolates of 2- alkylcycloalkanones (87-96% ee) with readily accessible chiral α-sulfinyl alcohols is described. Optimal stereoselection is achieved for each lithium enolate at a different reaction temperature in the range -40 to -100°C.
