85551-57-1Relevant academic research and scientific papers
Conformationally rigid chiral pyridine N-oxides as organocatalyst: Asymmetric allylation of aldehydes
Gnanamani, Elumalai,Someshwar, Nagamalla,Ramanathan, Chinnasamy Ramaraj
, p. 2101 - 2106 (2012)
A pyridine unit with a conformationally rigid chiral backbone has been designed and synthesized in an enantiomerically pure form to utilize in the Lewis base-catalyzed Sakurai-Hosomi-Denmark-type allylation reaction. The chiral pyridine N-oxide in 1:1 mix
A detailed NMR- and DFT-based study of the Sakurai-Hosomi-Yamamoto asymmetric allylation reaction
Hurem, David,Moiseev, Andrey G.,Simionescu, Razvan,Dudding, Travis
, p. 4440 - 4445 (2013)
A Lewis acid complex between benzaldehyde and the silver catalyst was detected by 31P NMR and shown to be the direct precursor to allylation within the Sakurai-Hosomi-Yamamoto reaction. Structural and thermochemical hybrid-DFT calculations indicated that benzaldehyde predominantly formed an η1-σ-complex with the catalyst; however, two other competing conformers involving different coordination modes were found, including an activated μ2-bound complex. The differences in 31P NMR shifts upon complexation were calculated by the gauge-independent atomic orbital (GIAO-DFT) method for each conformer. The minimum energy conformer was found to correlate well with chemical shift trends observed experimentally, and an analysis of Mullikan charge populations revealed that the carbonyl carbon of the highest-energy conformer was the most electron-deficient. Furthermore, one minor and three major silicon intermediates were detected by 29Si NMR and, with the aid of 1H- 29Si HSQC, were assigned by comparison with parent compounds and GIAO-DFT calculations. Finally, a tentative mechanism was proposed based on these findings.
Chiral bipyridine-annulated bicyclo[3.3.1]nonane N-oxide organocatalysts for stereoselective allylation and hydrosilylation reactions
?eimyt?, Simona,Ston?ius, Sigitas
supporting information, (2020/12/21)
The synthesis of chiral C2-symmetric bis(bipyridine N,N′-dioxide) and bis(bipyridine N-monooxide) derivatives featuring bipyridine-annulated bicyclo[3.3.1]nonane framework is reported. The new Lewis basic bipyridine N,N′-dioxides exhibited good
Emergence of Highly Enantioselective Catalytic Activity in a Helical Polymer Mediated by Deracemization of Racemic Pendants
Ikai, Tomoyuki,Ando, Mitsuka,Ito, Masaki,Ishidate, Ryoma,Suzuki, Nozomu,Maeda, Katsuhiro,Yashima, Eiji
supporting information, p. 12725 - 12735 (2021/08/24)
Any polymers composed of racemic repeating units are obviously optically inactive and hence chiral functions, such as asymmetric catalysis, will not be expected at all. Contrary to such a preconceived notion, we report an unprecedented helical polymer-based highly enantioselective organocatalyst prepared by polymerization of a racemic monomer with no catalytic activity. Both the right- and left-handed helical poly(biarylylacetylene)s (PBAs) composed of dynamically racemic 2-arylpyridyl-N-oxide monomer units with N-oxide moieties located in the vicinity of the helical polymer backbone can be produced by noncovalent interaction with a chiral alcohol through deracemization of the biaryl pendants. The macromolecular helicity and the axial chirality induced in the PBAs are retained ("memorized") after complete removal of the chiral alcohol. Accordingly, the helical PBAs with dual static memory of the helicity and axial chirality show remarkable enantioselectivity (86% ee) for the asymmetric allylation of benzaldehyde. The enantioselectivity is slightly lower than that (96% ee) of the homochiral PBAs prepared from the corresponding enantiopure (R)- and (S)-monomers, but is comparable to that (88% ee) of the helical PBA composed of nonracemic monomers of ca. 60% ee.
A chiral oxazoline for catalytic enantioselective Nozaki-Hiyama-Kishi allylation and vinylation of aldehydes
Chen, Chinpiao,Kumbhar, Sharad V.
, (2020/09/22)
Asymmetric allylation and vinylation of aldehydes with allyl halides and vinyl halides have been achieved using the chromium(II)-oxazoline catalyst. The catalyst promotes the highly efficient enantioselective Nozaki–Hiyama-Kishi (NHK) allylation of aldehydes using allyl bromide, producing the corresponding homoallylic alcohols in good yields (up to 84%) and a high level of enantioselectivity (up to 98% ee). Meanwhile, the NHK vinylation of aldehydes produce desired allylic alcohols in satisfactory yields (up to 88%) and a high level of enantioselectivity (up to 97% ee). We developed a reliable and milder protocol for preparing chiral homoallylic and allylic alcohols.
Highly Enantioselective Allylation Reactions of Aldehydes with Allyltrimethylsilane Catalyzed by a Chiral Oxazaborolidinium Ion
Kim, Taehyeong,Jeong, Hye-Min,Venkateswarlu, Anipireddy,Ryu, Do Hyun
supporting information, p. 5198 - 5201 (2020/07/15)
A highly enantioselective allylation reaction of aldehydes with silyl reagents was developed for the synthesis of a variety of chiral homoallylic alcohols. In the presence of a chiral oxazaborolidinium ion (COBI) catalyst, the reaction proceeded in high yield (up to 99percent) with excellent asymmetric induction (up to 99percent ee).
3,3′-Bithiophene-Based Chiral Bisphosphine Oxides as Organocatalysts in Silicon-Derived Lewis Acid Mediated Reactions
Benaglia, Maurizio,Benincori, Tiziana,Raimondi, Laura Maria,Rossi, Sergio
, p. 535 - 546 (2020/03/27)
This account summarizes the development of new biheteroaromatic chiral bisphosphine oxides. 3,3′-Bithiophene-based phosphine oxides (BITIOPOs) have been successfully used as organocatalysts to promote Lewis base catalyzed, Lewis acid mediated stereoselective transformations. These highly electron-rich compounds, in combination with trichorosilyl derivatives (allyltrichlorosilane and silicon tetrachloride), generate hypervalent silicon species that act as chiral Lewis acids in highly diastereo- and enantioselective organic reactions. Several relevant examples related to these applications are discussed in detail. 1 Introduction 2 The BITIOPO Family 3 Enantioselective Opening of Epoxides 4 Enantioselective Allylation of Aldehydes 5 Stereoselective Direct (Double) Aldol-Type Reaction with Ketones 6 Stereoselective Direct Aldol-Type Reaction with Ester Derivatives 7 Conclusions.
Bi(cyclopentyl)diol-Derived Boronates in Highly Enantioselective Chiral Phosphoric Acid-Catalyzed Allylation, Propargylation, and Crotylation of Aldehydes
Yuan, Jinping,Jain, Pankaj,Antilla, Jon C.
, p. 12988 - 13003 (2020/11/23)
In this study, we disclose the catalytic addition of bi(cyclopentyl)diol-derived boronates to aldehydes promoted by chiral phosphoric acids, allowing for the formation of enantioenriched homoallylic, propargylic, and crotylic alcohols (up to >99% enantiom
Enantioselective Allylation of Oxocarbenium Ions Catalyzed by Bi(OAc)3/Chiral Phosphoric Acid
Cheng, Jin-Pei,Li, Xin,Pan, Yu-Liang,Wang, Jie,Yang, Chen,Zheng, Han-Liang
, p. 8069 - 8076 (2020/09/21)
Phthalides as the crucial core skeletons are found extensively in natural products and biological active molecules. Herein we disclose an asymmetric allylation of 3-hydroxyisobenzofuran-1(3H)-ones with boron allylation reagents to construct chiral phthali
Copper(I) Diphosphine Bifluoride Complexes as Efficient Preactivated Catalysts for Nucleophilic Addition on Unsaturated Functional Groups
Rasson, Corentin,Riant, Olivier
supporting information, p. 835 - 840 (2020/02/13)
Herein we report the synthesis of a family of copper(I) diphosphine bifluoride complexes, their characterization, and their use as efficient preactivated catalysts for nucleophilic copper addition of pronucleophiles on unsaturations. Their use as mechanistic probes is also highlighted by the identification of two copper deuterides.
