132154-59-7Relevant academic research and scientific papers
Ruthenium-catalyzed tandem-isomerization/asymmetric transfer hydrogenation of allylic alcohols
Slagbrand, Tove,Lundberg, Helena,Adolfsson, Hans
, p. 16102 - 16106 (2015/01/09)
A one-pot procedure for the direct conversion of racemic allylic alcohols to enantiomerically enriched saturated alcohols is presented. The tandem-isomerization/ asymmetric transfer hydrogenation process is efficiently catalyzed by [{Ru(p-cymene)Cl2}2] in combination with the a-amino acid hydroxyamide ligand 1, and performed under mild conditions in a mixture of ethanol and THF. The saturated alcohol products are isolated in good to excellent chemical yields and in enantiomeric excess up to 93%.
Insights into the asymmetric heterogeneous catalysis in porous organic polymers: Constructing A TADDOL-Embedded chiral catalyst for studying the structure-activity relationship[ ]
An, Wan-Kai,Han, Man-Yi,Wang, Chang-An,Yu, Si-Min,Zhang, Yuan,Bai, Shi,Wang, Wei
supporting information, p. 11019 - 11028,10 (2014/12/09)
Construction of porous organic polymers (POPs) as asymmetric catalysts remains as an important but challenging task. Herein, we exploit the "bottom-up" strategy to facilely synthesize an α,α, α,α-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL)-based chiral porous polymer (TADDOL-CPP) for highly efficient asymmetric catalysis. Constructed through the covalent linkages among the three-dimensional rigid monomers, TADDOL-CPP possesses hierarchical porous structure, high Brunauer-Emmett-Teller (BET) surface area, together with abundant and uniformly-distributed chiral sites. In the presence of [Ti(OiPr)4], TADDOL-CPP acts as a highly efficient and recyclable catalyst in the asymmetric addition of diethylzinc (Et2Zn) to aromatic aldehydes. Based on the direct observation of the key intermediates, the reaction mechanism has been revealed by solid-state 13C magic-angle spinning (MAS) NMR spectroscopy. In combination with the catalytic testing results, characterization on the working catalyst provides further information for understanding the structure-activity relationship. We suggest that the catalytic activity of TADDOL-CPP is largely affected by the structural rigidity, cooperative catalysis, local chiral environment, and hierarchical porous framework. We expect that the information obtained herein will benefit to the designed synthesis of robust POP catalysts toward practical applications.
Functional-group-tolerant, nickel-catalyzed cross-coupling reaction for enantioselective construction of tertiary methyl-bearing stereocenters
Wisniewska, Hanna M.,Swift, Elizabeth C.,Jarvo, Elizabeth R.
supporting information, p. 9083 - 9090 (2013/07/26)
The first Negishi nickel-catalyzed stereospecific cross-coupling reaction of secondary benzylic esters is reported. A series of traceless directing groups is evaluated for ability to promote cross-coupling with dimethylzinc. Esters with a chelating thioether derived from commercially available 2-(methylthio)acetic acid are most effective. The products are formed in high yield and with excellent stereospecificity. A variety of functional groups are tolerated in the reaction including alkenes, alkynes, esters, amines, imides, and O-, S-, and N-heterocycles. The utility of this transformation is highlighted in the enantioselective synthesis of a retinoic acid receptor agonist and a fatty acid amide hydrolase inhibitor.
(R)-(+)-N-methylbenzoguanidine ((R)-NMBG) catalyzed kinetic resolution of racemic secondary benzylic alcohols with free carboxylic acids by asymmetric esterification
Nakata, Kenya,Shiina, Isamu
supporting information; experimental part, p. 7092 - 7096 (2011/11/04)
(R)-(+)-N-Methylbenzoguanidine ((R)-NMBG) was found to function as an efficient acyl-transfer catalyst for the kinetic resolution of racemic secondary benzylic alcohols in the presence of achiral carboxylic acids and pivalic anhydride. The use of a tertiary amine in this reaction is not necessary to attain good chemical yields of the products. It was determined that diphenylacetic acid could be employed as the most suitable acyl donor for achieving a high enantioselectivity for the kinetic resolution of the racemic secondary benzylic alcohols having normal aliphatic alkyl chains at the C-1 positions. On the other hand, a less-hindered carboxylic acid, such as 3-phenylpropanoic acid, functioned as a better acyl donor for the kinetic resolution of racemic secondary benzylic alcohols having branched aliphatic alkyl chains at the C-1 positions.
Catalytic asymmetric addition of diethylzinc to aldehydes via chiral, non-racemic β-hydroxy and β-methoxy salicylhydrazone catalysts
Banerjee, Sucharita,Ferrence, Gregory M.,Hitchcock, Shawn R.
scheme or table, p. 837 - 845 (2010/11/02)
(1S,2S)-Pseudoephedrine and (1S,2S)-pseudonorephedrine have been converted to their corresponding hydrazines and condensed with either o-salicylaldehyde or 2-hydroxy-1-naphthaldehyde to afford a series of β- hydroxysalicylhydrazones that have been employed in the asymmetric addition of diethylzinc to 2-naphthaldehyde in up to 56% ee. In addition to this, the Ephedra hydrazines were also condensed with the o-hydroxyacetophenone derivative to form related hydrazones. The use of these corresponding hydrazones in the asymmetric addition reaction with the diethylzinc did not yield improved enantioselectivities. Finally, Enders' hydrazine was used as a chiral scaffold for the synthesis of β-methoxysalicylhydrazones. These compounds were employed in the asymmetric addition of diethylzinc to a variety of aromatic aldehydes with enantiomeric excesses as high as 68% ee.
Aromatic motifs in the design of Ephedra ligands for application in the asymmetric addition of diethylzinc to aldehydes and diphenylphosphinoylimines
Banerjee, Sucharita,Camodeca, Anthony J.,Griffin, Gregory G.,Hamaker, Christopher G.,Hitchcock, Shawn R.
scheme or table, p. 549 - 557 (2010/10/02)
Using N-benzylephedrine as a model, a collection of N-arylmethylephedrine derivatives has been prepared. These derivatives were prepared by treatment of ephedrine with selected aldehydes to create oxazolidines 8a-e. Reduction of the oxazolidines with lith
Highly enantioselective arylation of aldehydes and ketones using AlArEt2(THF) as aryl sources
Zhou, Shuangliu,Wu, Kuo-Hui,Chen, Chien-An,Gau, Han-Mou
supporting information; experimental part, p. 3500 - 3505 (2009/09/30)
A series of AlArEt2(THF) (Ar = Ph (la), 4-MeC6H 4 (1b), 4-MeOC6H 4 (1c), 4-Me 3SiC6H4 (1d), 2-naphthyl (le)) were synthesized from reactions of AlEt2Br(THF) with ArMgBr. In CDC13 solution, the 1H NMR spectra showed that AlArEt2(THF) compounds exist as a mixture of four species of formulas of AlAr xEt3-x (THF) (x = 0, 1, 2, or 3). AlArEt2(THF) compounds were found to be superior and atom-economic reagents for asymmetric aryl additions to organic carbonyls. Aryl additions of AlArEt2(THF) to aldehydes catalyzed by the titanium(IV) complex of (R)-H8-BINOL were efficient with a short reaction time of 1 h, affording aryl addition products as exclusive or main products in high yields and excellent enantioselectivities of up to 98% ee. Although ethyl additions to aldehydes occurred in minor extent, this study demonstrates that increasing the amount of AlArEt2(THF) from 1.2 to 1.4 or to 1.6 equiv significantly improved the aryl addition products of up to >99%. On the other hand, asymmetric arylations of AlArEt2(THF) to ketones employing a titanium(IV) catalyst of (S)-BINOL produced optically active tertiary alcohols exclusively in excellent enantioselectivities of up to 94% ee.
Synthesis of a new 1,4-aminoalcohol and its use as catalyst in the enantioselective addition of organozinc to aldehydes
Scarpi, Dina,Galbo, Fabrizio Lo,Guarna, Antonio
, p. 1409 - 1414 (2007/10/03)
The synthesis of a new enantiopure, conformationally constrained 1,4-aminoalcohol is reported, starting from commercially available reagents from the chiral pool. This 1,4-aminoalcohol was used as chiral ligand in the addition of Et2Zn to aldehydes (best ee 98%) and in the synthesis of chiral propargylic alcohols (best ee 70%) by alkynylzinc species.
Asymmetric synthesis of functionalized diarylmethanols catalyzed by a new γ-amino thiol
Wu, Ping-Yu,Wu, Hsyueh-Liang,Uang, Biing-Jiun
, p. 833 - 835 (2007/10/03)
A mild asymmetric arylation of aromatic aldehydes catalyzed by γ-amino thiol 5 gave the corresponding diarylmethanols with 95 to >99.5% ee.
Asymmetric addition of phenylacetylene to aldehydes catalyzed by β-sulfonamide alcohol-titanium complex
Xu, Zhaoqing,Lin, Li,Xu, Jiangke,Yan, Wenjin,Wang, Rui
, p. 506 - 514 (2007/10/03)
A series of β-sulfonamide alcohol ligands were synthesized from L-phenylalanine. Titanium complexes of these compounds were used to catalyze the asymmetric addition of phenylacetylene to a number of aldehydes. When the conditions were optimized, 20 mol % of ligand 8a catalyzed the reaction with high enantioselectivity (up to 98% ee) and good yield (up to 92%). When a small amount of MeOH was added to the reaction as a modifier, as little as 5 mol % of ligand was required to efficiently catalyze the reaction under very mild conditions, resulting in an ee of up to 99% and good yield.
