761434-35-9Relevant academic research and scientific papers
Highly enantioselective epoxidation of 2-methylnaphthoquinone (vitamin K3) mediated by new cinchona alkaloid phase-transfer catalysts
Berkessel, Albrecht,Guixa, Maria,Schmidt, Friederike,Neudoerfl, Joerg M.,Lex, Johann
, p. 4483 - 4498 (2007)
In the area of catalytic asymmetric epoxidation, the highly enantioselective transformation of cyclic enones and quinones is an extremely challenging target. With the aim to develop new and highly effective phase-transfer catalysts for this purpose, we co
A flexible strategy for the synthesis of bifunctional 6′-(thio)-urea containing Cinchona alkaloid ammonium salts
Sch?rgenhumer, Johannes,Otte, Stefan,Haider, Victoria,Novacek, Johanna,Waser, Mario
supporting information, (2019/12/09)
A flexible and functional group tolerant synthesis route to access a structurally diverse collection of bifunctional 6′-(thio)-urea containing Cinchona alkaloid-based chiral quaternary ammonium salts has been developed. This route gives access to more than 25 different novel urea- and thiourea-containing ammonium salt derivatives, which were not accessible so far.
Enantioselective Ammonium Ylide Mediated One-Pot Synthesis of Highly Substituted γ-Butyrolactones
Drennhaus, Till,?hler, Laura,Djalali, Saveh,H?fmann, Svenja,Müller, Clemens,Pietruszka, J?rg,Worgull, Dennis
supporting information, p. 2385 - 2396 (2020/04/30)
An ammonium ylide mediated access towards trans-β,γ-disubstituted, all-trans-α,β,γ-trisubstituted, and α,α,β,γ-tetrasubstituted γ-butyrolactones bearing a broad variety of functionalities was developed. Starting from widely accessible benzylidene Meldrum's acid derivatives and α-bromo carbonyl compounds, γ-butyrolactones were obtained in yields between 32–99% with up to excellent diastereoselectivities (>95:5) via a DABCO-mediated [2+1] annulation. Utilization of enantiomerically pure cinchona alkaloid derivatives enables the first asymmetric ammonium ylide mediated method to provide (3R,?4R)-β,γ-disubstituted and (2R,?3R,?4R)-α,β,γ-trisubstituted γ-butyrolactones in moderate to good yields with up to very good enantiomeric ratios (97:3). The scalability of the transformation was proven while determining the absolute configuration. (Figure presented.).
Enantioselective Organocatalyzed Direct α-Thiocyanation of Cyclic β-Ketoesters by N -Thiocyanatophthalimide
Qiu, Jiashen,Wu, Di,Karmaker, Pran Gopal,Yin, Hongquan,Chen, Fu-Xue
supporting information, p. 1600 - 1603 (2018/03/23)
A new electrophilic thiocyanation reagent, N-thiocyanatophthalimide, was synthesized and applied to the first example of catalytic asymmetric electrophilic α-thiocyanation of various cyclic β-ketoesters by the bifunctional cinchona alkaloid catalysis. Thus, a variety of chiral α-thiocyanato β-ketoesters with a quaternary carbon center have been achieved in excellent yields (up to 99%) and high enantioselectivities (up to 94% ee) in a convenient manner.
Anti-Selective Asymmetric Nitro-Michael Reaction of Furanones: Diastereocontrol by Catalyst
Sekikawa, Tohru,Kitaguchi, Takayuki,Kitaura, Hayato,Minami, Tatsuya,Hatanaka, Yasuo
, p. 646 - 649 (2016/03/01)
Catalyst-controlled switching of diastereoselectivity from high syn-selectivity (>98/2 dr, syn) to anti-selectivity (up to 96/4 dr, anti) of the asymmetric nitro-Michael reaction of furanones is described. Anti-diastereoselectivity of the nitro-Michael reaction is very rare. With 0.1-5 mol % loadings of an epi-quinine catalyst, the reaction of 5-substituted 2(3H)-furanones with nitroalkenes smoothly proceeded to give the anti-Michael adducts in good yields (up to 95%) with excellent diastereo- and enantioselectivities (up to 96/4 dr, anti; up to 99% ee). DFT calculations support a model that accounts the high anti-diastereoselectivity. (Chemical Equation Presented).
Syn-selective nitro-Michael addition of furanones to β,β-disubstituted nitroalkenes catalyzed by epi-quinine derivatives
Sekikawa, Tohru,Kitaura, Hayato,Kitaguchi, Takayuki,Minami, Tatsuya,Hatanaka, Yasuo
, p. 2985 - 2989 (2016/07/06)
Epi-quinine-catalyzed asymmetric nitro-Michael addition of furanones to β,β,-disubstituted nitroalkenes is described. The reaction proceeded smoothly with 1-5 mol % loadings of epi-quinine catalysts at room temperature, giving the corresponding Michael adducts in high yields (72-93%) with extremely high diastereo- and enantioselectivities (>98/2 dr, syn major; 95-99% ee). This reaction provides an effective and straightforward method for constructing all-carbon quaternary stereogenic centers adjacent to oxygen-containing quaternary stereogenic centers.
Enantioselective α-hydroxylation of β-keto esters catalyzed by cinchona alkaloid derivatives
Wang, Yakun,Li, Zhi,Xiong, Ting,Zhao, Jingnan,Meng, Qingwei
, p. 2155 - 2160 (2014/11/08)
A highly efficient α-hydroxylation of β-keto esters catalyzed by cupreidine in the presence of cumyl hydroperoxide (CHP) was achieved. The reaction was applied to a wide variety of β-keto esters to give products in high yields (up to 95%) with excellent enantioselectivities (up to 97% ee). The reaction had been successfully scaled up to a gram quantity and (S)-5-chloro-2-hydroxy-1-oxo-2,3-dihydro-1H-indene-2-carboxylate - the important intermediate of Indoxacarb were obtained in 96% yield with 86% ee. The enantiomeric excess could be improved to 99% by crystallization, and this method has prospect of industrial application for its advantages of enantioselectivity, ease of catalyst preparation and reclamation of catalyst. Georg Thieme Verlag Stuttgart. New York.
The enantioselective trifluoromethylation of aromatic aldehydes by quaternary ammonium bromide and (IPr)CuF at low catalyst loading
Wu, Shaoxiang,Guo, Jiyi,Sohail, Muhammad,Cao, Chengyao,Chen, Fu-Xue
, p. 19 - 29 (2013/04/23)
A general catalytic enantioselective trifluoromethylation of aromatic aldehydes using (IPr)CuF and quinidine-derived quaternary ammonium salt as catalysts has been developed. A wide range of aromatic aldehydes are converted to the corresponding products in up to 92% yield and 81% ee at 2 mol% of catalyst loading.
Asymmetric trifluoromethylation of aromatic aldehydes by cooperative catalysis with (IPr)CuF and quinidine-derived quaternary ammonium salt
Wu, Shaoxiang,Zeng, Wei,Wang, Qi,Chen, Fu-Xue
supporting information, p. 9334 - 9337 (2013/01/15)
A general enantioselective trifluoromethylation of aldehydes has been developed using (IPr)CuF and quinidine-derived quaternary ammonium salt as the cooperative catalyst. Thus, a wide range of aromatic aldehydes have been converted to the corresponding products in up to 92% yield and 81% ee at 2 mol% of catalyst loading. The greatly enhanced activity and enantioselectivity result from the initiative generation of active [(IPr)CuCF3] as well as additional coordination activation of other copper species.
Organocatalytic sequential Michael reactions: Stereoselective synthesis of multifunctionalized tetrahydroindan derivatives
He, Peng,Liu, Xiaohua,Shi, Jian,Lin, Lili,Feng, Xiaoming
supporting information; experimental part, p. 936 - 939 (2011/04/23)
Multifunctionalized tetrahydroindan derivatives with four stereocenters were constructed via two sequential Michael reactions between cyclic γ,δ-unsaturated-β-ketoester and nitroalkenes initiated with 0.5-2 mol % of cinchona alkaloid based bifunctional organocatalysts and then with 1 equiv of tetramethylguanidine for cyclization. The desired products could be obtained in high yields (up to 99% yield) with excellent enantioselectivities (95-99% ee) as well as diastereoselectivities (up to >99:1 dr) even on a gram scale.(Figure Presented)
