56438-73-4Relevant articles and documents
Diastereoselective Cyclobutenol Synthesis: A Heterogeneous Palladium-Catalyzed Oxidative Carbocyclization-Borylation of Enallenols
Li, Man-Bo,Posevins, Daniels,Gustafson, Karl P. J.,Tai, Cheuk-Wai,Shchukarev, Andrey,Qiu, Youai,B?ckvall, Jan-E.
, p. 210 - 215 (2019)
A highly selective and efficient oxidative carbocyclization/borylation of enallenols catalyzed by palladium immobilized on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was developed for diastereoselective cyclobutenol synthesis. The heter
Efficient Heterogeneous Palladium-Catalyzed Oxidative Cascade Reactions of Enallenols to Furan and Oxaborole Derivatives
Li, Man-Bo,Posevins, Daniels,Geoffroy, Antoine,Zhu, Can,B?ckvall, Jan-E.
, p. 1992 - 1996 (2020)
A heterogeneous palladium-catalyzed oxidative cyclization of enallenols has been developed for the construction of highly substituted furan and oxaborole derivatives. The heterogeneous catalyst (Pd-AmP-MCF) exhibits high activity, high site- and stereoselectivity, and efficient palladium recyclability in the transformations.
Chemodivergent and Diastereoselective Synthesis of γ-Lactones and γ-Lactams: A Heterogeneous Palladium-Catalyzed Oxidative Tandem Process
Li, Man-Bo,Inge, A. Ken,Posevins, Daniels,Gustafson, Karl P. J.,Qiu, Youai,B?ckvall, Jan-E.
, p. 14604 - 14608 (2018)
A palladium-catalyzed oxidative tandem process of enallenols was accomplished within a homogeneous/heterogeneous catalysis manifold, setting the stage for the highly chemodivergent and diastereoselective synthesis of γ-lactones and γ-lactams under mild co
Synthesis of a Mechanically Planar Chiral Rotaxane Ligand for Enantioselective Catalysis
Goldup, Stephen M.,Heard, Andrew W.
supporting information, p. 994 - 1006 (2020/04/08)
Rotaxanes are interlocked molecules in which a molecular ring is trapped on a dumbbell-shaped axle because of its inability to escape over the bulky end groups, resulting in a so-called mechanical bond. Interlocked molecules have mainly been studied as components of molecular machines, but the crowded, flexible environment created by threading one molecule through another has also been explored in catalysis and sensing. However, so far, the applications of one of the most intriguing properties of interlocked molecules, their ability to display stereogenic units that do not rely on the stereochemistry of their covalent subunits, termed “mechanical chirality,” have yet to be properly explored, and prototypical demonstration of the applications of mechanically chiral rotaxanes remain scarce. Here, we describe a mechanically planar chiral rotaxane-based Au complex that mediates a cyclopropanation reaction with stereoselectivities that are comparable with the best conventional covalent catalyst reported for this reaction. Molecules that exist in non-identical mirror image forms are referred to as chiral. Chirality can arise because of various molecular features in which atoms are held in fixed orientations that are themselves chiral, and typically such “stereogenic units” are maintained by direct bonds between atoms. Molecular chirality can also arise by threading a dumbbell-shaped molecule through a molecular ring to generate a rotaxane. However, these molecules have not been investigated significantly because until recently they were extremely hard to make in one mirror image form. Here, we report the first example of a catalyst based on such a “mechanically chiral” rotaxane. Catalysis with chiral molecules is extremely important in modern chemistry because it is one of the most efficient ways to make chiral molecules for applications in healthcare and other areas. Our results demonstrate that mechanically chiral molecules are a promising and underexplored platform for generating such catalysts. We report an enantioselective catalyst based on a “mechanically chiral” rotaxane. Catalysis with chiral molecules is extremely important in modern chemistry because it is one of the most efficient ways to make chiral molecules for applications in many areas. Our results demonstrate, for the first time, that mechanically chiral molecules are a promising and underexplored platform for generating such catalysts. We achieve enantioselectivities for the AuI-catalyzed Ohe-Uemura cyclopropanation of benzoate esters comparable to previously reported covalent catalysts.
Enantioselective Addition of Alkynyl Esters and Ethers to Aldehydes Catalyzed by a Cyclopropyl Amino Alcohol Based Zinc Catalyst
Bian, Qinghua,Li, Fengqi,Li, Shuoning,Ma, Sijie,Walsh, Patrick J.,Wang, Lifeng,Wang, Min,Zhong, Jiangchun,Zhou, Yun
supporting information, p. 60 - 64 (2019/12/30)
A novel and highly enantioselective synthesis of hydroxyalkynyl esters and ethers through the asymmetric addition of alkynyl esters or ethers to aldehydes promoted by a cyclopropyl amino alcohol based zinc catalyst has been developed. The method afforded a library of new enantioenriched hydroxyalkynol esters and ethers (up to 93percent yield; 95percent ee), and it was compatible with a broad range of functional groups. Moreover, it could be used in the synthesis of carbon-chain-elongated enantioenriched hydroxyalkynol esters and (2 R,5 R)-musclide-A1, a cardiotonic potentiating principle from musk.
Fluoride-Catalyzed Esterification of Amides
Wu, Hongxiang,Guo, Weijie,Daniel, Stelck,Li, Yue,Liu, Chao,Zeng, Zhuo
supporting information, p. 3444 - 3447 (2018/02/21)
In recent years, it has been demonstrated that amide carbon–nitrogen bonds can be activated and selectively cleaved using transition metal catalysts. However, these methodologies have been restricted to specific amides; a one-to-one relationship exists between the catalytic system and the amides and also uses large amounts of transition-metal catalysts and ligands. Hence, we now report a general strategy for esterification of common amides using fluoride as a catalyst. This method shows high functional group tolerance, and notably it requires only a slight excess of the alcohol nucleophile, which is a rare case in transition-metal-free amide transformations. Moreover, this approach may provide a new understanding for further studies on esterification of amides and is expected to stimulate the development of alternative methods for direct functionalization of amides.
Divergent Elementoboration: 1,3-Haloboration versus 1,1-Carboboration of Propargyl Esters
Wilkins, Lewis C.,Soltani, Yashar,Lawson, James R.,Slater, Ben,Melen, Rebecca L.
supporting information, p. 7364 - 7368 (2018/05/03)
This work showcases the 1,3-haloboration reaction of alkynes in which boron and chlorine add to propargyl systems in a proposed sequential oxazoliumborate formation with subsequent ring-opening and chloride migration. In addition, the functionalization of
Stereoselective, Ag-Catalyzed Cyclizations to Access Polysubstituted Pyran Ring Systems: Synthesis of C1-C12 Subunit of Madeirolide A
Watanabe, Kazuhiro,Li, Jinming,Veerasamy, Nagarathanam,Ghosh, Ankan,Carter, Rich G.
, p. 1744 - 1747 (2016/05/19)
The exploration into the scope of a silver-catalyzed cyclization (AgCC) of propargyl benzoates for accessing pyran ring systems has been reported. The impact of the degree of substitution, nature of the substitution on the carbon backbone/benzoate moiety,
Palladium-Catalyzed [2+1] Cycloadditions Affording Vinylidenecyclopropanes as Precursors of 7-Membered Carbocycles
Lepronier, Aymeric,Achard, Thierry,Giordano, Laurent,Tenaglia, Alphonse,Buono, Gerard,Clavier, Herve
supporting information, p. 631 - 642 (2016/02/27)
Palladium(II) acetate in association with secondary phosphine oxides provides an efficient catalytic system for [2+1] cycloadditions starting from oxanorbornene derivatives and tertiary propargyl esters giving rise to vinylidenecyclopropanes. This reaction is specific to bidentate phosphinito-phosphinous acid ligands generated from secondary phosphine oxides. The [2+1] cycloaddition was found broad in scope with a high tolerance to various functional groups. Moreover, vinylidenecyclopropanes were straightforwardly converted into oxabicyclo[3.2.1]oct-2-ene derivatives through a palladium-catalyzed ring-expansion. Finally, the oxa bridge cleavage of oxatricyclic compounds yields functionalized 7-membered carbocycles.
A flexible approach to Pd-catalyzed carbonylations via aroyl dimethylaminopyridinium salts
Quesnel, Jeffrey S.,Fabrikant, Alexander,Arndtsen, Bruce A.
, p. 295 - 300 (2015/12/30)
4-Dimethylaminopyridine (DMAP) is shown to undergo Pd/PtBu3 catalyzed coupling with aryl halides and carbon monoxide to form electrophilic aroyl-DMAP salts. The reaction is easily scalable to prepare multigram quantities with low catalyst loadings, while the precipitation of these salts as they form leads to products with low impurities. These reagents rapidly react with a variety of nucleophiles, including those that contain potentially incompatible functional groups under standard carbonylative conditions.
