3968-67-0Relevant academic research and scientific papers
Stereospecific, Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling of Allylic Pivalates to Deliver Quaternary Stereocenters
Cobb, Kelsey M.,Rabb-Lynch, Javon M.,Hoerrner, Megan E.,Manders, Alex,Zhou, Qi,Watson, Mary P.
supporting information, p. 4355 - 4358 (2017/08/23)
Recognizing the importance of all-carbon, quaternary stereocenters in complex molecule synthesis, a stereospecific, nickel-catalyzed cross-coupling of allylic pivalates with arylboroxines to deliver products equipped with quaternary stereocenters and internal alkenes was developed. The enantioenriched allylic pivalate starting materials are readily prepared, and a variety of functional groups can be incorporated on both the allylic pivalate and the arylboroxine. Additional advantages include the use of a commercially available and air-stable Ni(II) salt and BISBI ligand, mild reaction conditions, and high yields and ee's. The observed stereoinversion of this reaction is consistent with an open transition state in the oxidative addition step.
Modular, catalytic enantioselective construction of quaternary carbon stereocenters by sequential cross-coupling reactions
Potter, Bowman,Edelstein, Emma K.,Morken, James P.
, p. 3286 - 3289 (2016/07/13)
The catalytic Suzuki-Miyaura cross-coupling with chiral γ,γ-disubstituted allylboronates in the presence of RuPhos ligand occurs with high regioselectivity and enantiospecificity, furnishing nonracemic compounds with quaternary centers. Mechanistic experiments suggest that the reaction occurs by transmetalation with allyl migration, followed by rapid reductive elimination.
Entrapment of a chiral cobalt complex within silver: A novel heterogeneous catalyst for asymmetric carboxylation of benzyl bromides with CO2
Yang, Heng-Pan,Yue, Ying-Na,Sun, Qi-Long,Feng, Qiu,Wang, Huan,Lu, Jia-Xing
supporting information, p. 12216 - 12219 (2015/07/27)
A novel way to accommodate heterogeneous catalysis, CO2 fixation and asymmetric synthesis on one catalyst is reported. The [Co]@Ag composite was prepared for the first time and used for asymmetric carboxylation of benzyl bromides with CO2. All the procedures were performed under mild conditions. Moreover, the [Co]@Ag composite has terrific stability and reusability.
Chiral primary amine mediated conjugate addition of branched aldehydes to vinyl sulfone: Asymmetric generation of quaternary carbon centers
Zhu, Qiang,Lu, Yixin
supporting information; experimental part, p. 2235 - 2237 (2010/07/09)
Novel l-threonine-derived bifunctional organic catalysts containing primary amine and sulfonamide groups were utilized to promote asymmetric conjugate addition of α,α-disubstitued aldehydes to 1,1-bis(benzenesulfonyl) ethylene. The adducts with quaternary
Stereodivergent quaternization of 2-alkyl-2-p-tolylsulfinylacetonitriles: NMR spectroscopic evidence of planar and pyramidal benzylic carbanions
Ruano, Jose Luis Garcia,Martin-Castro, Ana M.,Tato, Francisco,Torrente, Esther,Poveda, Ana M.
supporting information; experimental part, p. 6317 - 6325 (2010/07/13)
Enantiomerically enriched α,α-disubstituted phenylacetonitriles have been readily prepared by stereo-selective quaternization of 2-alkyl-2-[2-(p-tolylsulfinyl)phenyl]acetonitriles with different alkylating electrophiles in the presence of bases. The use of potassium hexamethyldisilazane (KHMDS)/[18]crown-6 ether and NHMDS with alkyl halides afforded S,SS and R,SS diastereoisomers, respectively, in high enantiomeric purities, thus providing stereodivergent processes for synthesizing both isomers. The dependence of the stereochemical course of the reactions on the experimental conditions (mainly on the counterion) has been rationalized by assuming a planar or pyramidal structure for the benzylic carbanions. This hypothesis has been supported by NMR spectroscopic studies, which permit one to assign a chelated pyramidal structure to the sodium benzylic carbanions and an almost planar naked carbanionic structure to the potassium benzylic carbanions generated in the presence of [18]crown-6 ether.
Asymmetric construction of quaternary carbon centers by regio- and enantiocontrolled allylzincation
Nakamura, Masaharu,Inoue, Toshihiro,Sato, Akihito,Nakamura, Eiichi
, p. 2193 - 2196 (2007/10/03)
(equation presented) An allylic zinc reagent bearing a chiral bisoxazoline ligand adds to a substituted cyclopropenone acetal to produce an optically active cyclopropanone acetal possessing a quaternary chiral center in high yield with 97.8-99.8% ee. The
Synthesis and photochemistry of (2S,4R)- and (2R,4R)-1,2,3,4-tetrahydro-4-ethyl-1,1,4-trimethyl-3Z-ethylidene-2-naphthalenols
Miesen, F. W. A. M.,Dongen, J. L. J. van,Meijer, E. W.
, p. 307 - 317 (2007/10/02)
The synthesis and photochemistry of optically pure (2S,4R)- and (2R,4R)-1,2,3,4-tetrahydro-4-ethyl-1,1,4-trimethyl-3Z-ethyliden-2-naphthalenols 10a and 11a are described.Naphthalenols 10a and 11a were prepared in seven steps from 2-phenylbutanenitrile.Syn
