23985-58-2Relevant academic research and scientific papers
Asymmetric Diels-Alder, Michael, and aldol reactions using a planar chiral 1,3-oxazol-2(3H)-one derived from (R)-(+)-4-hydroxy-[2.2]paracyclophane
Cipiciani, Antonio,Fringuelli, Francesco,Piermatti, Oriana,Pizzo, Ferdinando,Ruzziconi, Renzo
, p. 2665 - 2670 (2002)
(+)-(R)-[2.2]Paracyclophane[4,5-d]-1,3-oxazol-2(3H)-one exhibiting planar chirality has been used as a chiral auxiliary in asymmetric Diels-Alder, Michael, and aldol reactions of α,β-unsaturated carboxy and enolate imides, respectively. The endo-exo- and face-diastereoselectivity is good and is controlled by the spatial relationship between the prochiral center and the C9-C10 ethylene bridge of the [2.2]paracyclophane moiety. The chiral auxiliary is easily removed and quantitatively recovered.
Anti-Selective enolboration-aldolization of propanoic acid
Ramachandran, P. Veeraraghavan,Chanda, Prem B.,Otoo, Barnabas
supporting information, p. 1289 - 1291 (2014/03/21)
A systematic examination of enolboration-aldolization of propanoic acid has led to an efficient synthesis of anti-β-hydroxy-α-methyl carboxylic acids in consistently high yields and diastereoselectivities by using B-bromodicyclohexylborane as the enolizat
MNBA-mediated β-lactone formation: Mechanistic studies and application for the asymmetric total synthesis of tetrahydrolipstatin
Shiina, Isamu,Umezaki, Yuma,Kuroda, Nobutaka,Iizumi, Takashi,Nagai, Shunsuke,Katoh, Takashi
, p. 4885 - 4901 (2012/07/30)
Various β-lactones were prepared from β-hydroxycarboxylic acids by intramolecular dehydration condensation using MNBA, an effective coupling reagent, along with a nucleophilic catalyst. The transition state that provides the desired 4-membered ring model system is disclosed by density functional theory (DFT) calculations, and the structural features of the transition form are discussed. This method was successfully applied to the asymmetric total synthesis of tetrahydrolipstatin (THL), an antiobestic drug used in clinical treatment to inhibit the activity of pancreatic lipase.
Rhenium-catalyzed reaction of carbonyl compounds with ketene silyl acetals
Nishiyama, Yutaka,Kaiba, Kenta,Umeda, Rui
experimental part, p. 793 - 795 (2010/03/24)
It was found that rhenium complex is an effective catalyst for the reaction of carbonyl compounds with ketene silyl acetals. A wide range of β-silyloxy esters is obtained by the treatment of carbonyl compounds with ketene silyl acetals in the presence of
Synthesis of 2-Arylethylamines by the Curtius Rearrangement
Schulze, Matthias
experimental part, p. 1461 - 1476 (2010/07/08)
2-Arylethylamine derivatives were synthesized using the Curtius reaction and with three different methods of preparing the acyl azide functional group. Carbamates derived from isocyanate were convenient protecting groups for alkylation of amines. Starting from benzaldehyde, amphetamine was prepared in three steps through an oxazolidin-2-one intermediate in 62% overall yield. Copyright Taylor & Francis Group, LLC.
Aldol reactions on solid phase. Sc(OTf)3-catalyzed aldol reactions of polymer-supported silyl enol ethers with aldehydes providing convenient methods for the preparation of 1,3-diol, β-hydroxy carboxylic acid, and β-hydroxy aldehyde libraries
Kobayashi, Shu,Hachiya, Iwao,Yasuda, Masaru
, p. 5569 - 5572 (2007/10/03)
Aldol reactions on solid phase have been achieved. In the presence of a catalytic amount of scandium triflate (Sc(OTf)3), polymer-supported silyl enol ethers reacted with aldehydes to afford the corresponding β-hydroxy thioester derivatives, which were reduced to 1,3-diol and β-hydroxy aldehyde derivatives, or hydrolyzed to β-hydroxy carboxylic acid derivatives.
The Phenyldimethylsilyl Group as a Masked Hydroxy Group
Fleming, Ian,Henning, Rolf,Parker, David C.,Plaut, Howard E.,Sanderson, Philip E. J.
, p. 317 - 338 (2007/10/02)
A phenyldimethylsilyl group attached to carbon can be converted into hydroxy group 1->5, with retention of configuration at the migrating carbon, by any of three main methods.The first involves protodesilylation, to remove the phenyl ring from the silicon atom, followed by oxidation of the resulting functionalized silicon atom using peracid or hydrogen peroxide.The second uses mercuric acetate for the same purpose, and can be combined in one pot with the oxidative step using peracetic acid.This method has a variant in which the mercuric ion is combined with palladium(II) acetate, both in less than stoichiometric amounts.The third uses bromine, which can also be used in one pot in conjuction with peracetic acid.In this method, but not in the method based on mercuric acetate, the peracetic acid may be buffered with sodium acetate.The method using bromine as the electrophile for removing the benzene ring has a more agreeable variant in which it is administered in the form of potassium bromide, which is oxidised to bromine by the peracetic acid.The scope and limitations of each of these methods are reported with a range of examples possessing between them many of the common functional groups.Simple benzene rings, alcohols, ethers, esters, amides and nitriles are compatible with all three methods, and ketones do not undergo Baeyer-Villiger reaction under any of the conditions.Amines, however, are oxidised to amine oxides.Ketones may be brominated in the third of the three main species.The absence of acid in the third method makes it especially valuable when the phenyldimethylsilyl group has a neighbouring nucleofugal group such as hydroxy or acetoxy.Carbon-carbon double bonds are incompatible with the methods, except for terminal monosubstituted double bonds, which can survive the conditions used in the first of the three methods.
Indenone synthesis. Improved synthetic protocol and effect of substitution on the intramolecular Friedel-Crafts acylation
Galatsis, Paul,Manwell, Jeffrey J.,Blackwell, James M.
, p. 1656 - 1659 (2007/10/02)
An improved protocol for the construction of substituted indenones is presented. Also the effect of substitution on the intramolecular Friedel-Crafts acylation was noted. Specifically, if there is no substitution at the 2-position of the indenone poor yields of cyclized material were obtained, if at all, while the substitution of a methyl or ethyl group greatly improved the yield of cyclized material. Placement of a large group (e. g., benzyl) resulted in a diminuation of the improved yield. The new synthetic procedure could, in principle, allow for the construction of 2,3-disubstituted indenones. One example of this reaction mode was presented.
STUDIES ON THE BASE-PROMOTED ENANTIOSELECTIVE ALDOL REACTION BETWEEN AN (S,S)-2-OXO-2-PROPIONYL-1,3,2-OXAZAPHOSPHORINANE AND BENZALDEHYDE
Gordon, Neil J.,Evans, Slayton A.
, p. 47 - 50 (2007/10/02)
The synthesis of an (S,S)-2-oxo-2-propionyl-1,3,2-oxazaphosphorinane, via the condensation of (S)-1-N-isopropylbutan-2-ol (3) with methyl dichloro phosphite (CH3OPCl2) followed by the Michaelis-Arbusov condensation reaction with propionyl chloride, will b
