4392-24-9Relevant articles and documents
The Reactivity of Benzyl Lithium Species is Regulated by Intermediate Structures
Kroesen, Ulrike,Knauer, Lena,Strohmann, Carsten
, p. 6232 - 6235 (2017)
The reaction of benzyl lithiums is an important aspect in organic and organometallic synthesis. Reported herein are detailed insights into the reactivity of benzyl lithiums as regulated by intermediate structures. By discussing the carbometalation of allylamines and the reaction of the formed benzyl-lithium compounds with electrophiles, the influence of the metal as well as the solvent on the electronic structure of the intermediate is described. This molecular structure strongly influences the reactivity of these intermediates. By choosing the appropriate reaction conditions, the regioselectivity of reactions with electrophiles can be regulated. With trimethylchlorosilane in n-pentane a selective reaction at the para-position takes place. In contrast, selective reaction at the benzylic position, with trimethylchlorostannane in tetrahydrofuran (THF) as a solvent, is accomplished.
Iridium-catalyzed regio- And enantioselective allylic esterification of secondary allylic alcohols with carboxylic acids
Shao, Ying,Sun, Jiangtao,Tang, Shengbiao,Wang, Changkai,Zhang, Peng
supporting information, p. 11080 - 11083 (2021/10/30)
We report herein an iridium-catalyzed asymmetric allylic esterification of racemic secondary allylic alcohols using free carboxylic acids as nucleophiles under mild conditions with broad functional group tolerance, exhibiting excellent regio- and enantios
Palladium-Catalyzed Allyl-Allyl Reductive Coupling of Allylamines or Allylic Alcohols with H2as Sole Reductant
Zhou, Xibing,Zhang, Guoying,Huang, Renbin,Huang, Hanmin
supporting information, p. 365 - 369 (2021/01/26)
Catalytic carbon-carbon bond formation building on reductive coupling is a powerful method for the preparation of organic compounds. The identification of environmentally benign reductants is key for establishing an efficient reductive coupling reaction. Herein an efficient strategy enabling H2 as the sole reductant for the palladium-catalyzed allyl-allyl reductive coupling reaction is described. A wide range of allylamines and allylic alcohols as well as allylic ethers proceed smoothly to deliver the C-C coupling products under 1 atm of H2. Kinetic studies suggested that the dinuclear palladium species was involved in the catalytic cycle.
Gold-Catalyzed Formal Hexadehydro-Diels-Alder/Carboalkoxylation Reaction Cascades
Wang, Hong-Fa,Guo, Lin-Na,Fan, Zhi-Bo,Tang, Tian-Hua,Zi, Weiwei
supporting information, p. 2676 - 2681 (2021/04/12)
A dual gold-catalyzed hexadehydro-Diels-Alder/carboalkoxylation cascade reaction is reported. In this transformation, the gold catalyst participated in the hexadehydro-Diels-Alder step, switching the mechanism from a radical type to a cationic one, and then the catalyst activated the resulting aryne to form an ortho-Au phenyl cation species, which underwent a carboalkoxylation rearrangement rather than the expected aryne-ene reaction.
Asymmetric [2+2] photocycloadditionviacharge transfer complex for the synthesis of tricyclic chiral ethers
Martínez-Gualda, Ana M.,Domingo-Legarda, Pablo,Rigotti, Thomas,Díaz-Tendero, Sergio,Fraile, Alberto,Alemán, José
supporting information, p. 3046 - 3049 (2021/03/29)
The asymmetric synthesis of chiral polycyclic ethers by an intramolecular [2+2] photocycloaddition is described. This process proceeded through a photocatalytically active iminium ion-based charge transfer (CT) complex under visible light irradiation. In this way a stereocontrolled [2+2] photocycloaddition is enabled leading to tricyclic products with good enantiomeric ratios.
Stereodivergent Nucleophilic Additions to Racemic β-Oxo Acid Derivatives: Fast Addition Outcompetes Stereoconvergence in the Archetypal Configurationally Unstable Electrophile
Crawford, Evan T.,De Jesús Cruz, Pedro,Johnson, Jeffrey S.,Liu, Shubin
, p. 16264 - 16273 (2021/10/21)
Additions of carbon nucleophiles to racemic α-stereogenic β-oxo acid derivatives that deliver enantiomerically enriched tertiary alcohols are valuable, but uncommon. This article describes stereodivergent Cu-catalyzed borylative cyclizations of racemic β-oxo acid derivatives bearing tethered pro-nucleophilic olefins to deliver highly functionalized cyclopentanols containing four contiguous stereogenic centers. The reported protocol is applicable to a range of β-oxo acid derivatives, and the diastereomeric products are readily isolable by typical chromatographic techniques. α-Stereogenic-β-keto esters are typically thought to have extreme or spontaneous configurational fragility, but mechanistic studies for this system reveal an unusual scenario wherein productive catalysis occurs on the same time scale as background substrate racemization and completely outcompetes on-cycle epimerization, even under the basic conditions of the reaction.
Regiospecific Synthesis of Calcium-Independent Daptomycin Antibiotics using a Chemoenzymatic Method
Mupparapu, Nagaraju,Lin, Yu-Hsin Cindy,Kim, Tae Ho,Elshahawi, Sherif I.
supporting information, p. 4176 - 4182 (2021/02/01)
Daptomycin (DAP) is a calcium (Ca2+)-dependent FDA-approved antibiotic drug for the treatment of Gram-positive infections. It possesses a complex pharmacophore hampering derivatization and/or synthesis of analogues. To mimic the Ca2+-binding effect, we used a chemoenzymatic approach to modify the tryptophan (Trp) residue of DAP and synthesize kinetically characterized and structurally elucidated regiospecific Trp-modified DAP analogues. We demonstrated that the modified DAPs are several times more active than the parent molecule against antibiotic-susceptible and antibiotic-resistant Gram-positive bacteria. Strikingly, and in contrast to the parent molecule, the DAP derivatives do not rely on calcium or any additional elements for activity.
PHARMACEUTICAL COMPOSITION FOR PREVENTING OR TREATING AGING-RELATED DISEASES CONTAINING DECURSIN DERIVATIVE AS ACTIVE INGREDIENT
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Paragraph 0056-0057, (2020/02/27)
A composition for preventing or treating an aging-related disease includes a novel decursin derivative as an active ingredient, wherein the novel decursin derivative has exhibited an excellent effect of inhibiting progerin expression and excellent effect of inhibiting binding between progerin and lamin A, and it has been confirmed that the novel decursin derivative prolongs the survival period of animal models in which progerin was induced.
Enantioselective Allenoate-Claisen Rearrangement Using Chiral Phosphate Catalysts
Ellwart, Mario,Gensch, Tobias,Han, Seo-Jung,Lin, Hsin-Hui,Miró, Javier,Sigman, Matthew S.,Toste, F. Dean
supporting information, p. 6390 - 6399 (2020/04/27)
Herein we report the first highly enantioselective allenoate-Claisen rearrangement using doubly axially chiral phosphate sodium salts as catalysts. This synthetic method provides access to β-amino acid derivatives with vicinal stereocenters in up to 95percent ee. We also investigated the mechanism of enantioinduction by transition state (TS) computations with DFT as well as statistical modeling of the relationship between selectivity and the molecular features of both the catalyst and substrate. The mutual interactions of charge-separated regions in both the zwitterionic intermediate generated by reaction of an amine to the allenoate and the Na+-salt of the chiral phosphate leads to an orientation of the TS in the catalytic pocket that maximizes favorable noncovalent interactions. Crucial arene-arene interactions at the periphery of the catalyst lead to a differentiation of the TS diastereomers. These interactions were interrogated using DFT calculations and validated through statistical modeling of parameters describing noncovalent interactions.
Radical-Cation Cascade to Aryltetralin Cyclic Ether Lignans Under Visible-Light Photoredox Catalysis
Wang, Qian,Xiang, Jia-Chen,Zhu, Jieping
supporting information, p. 21195 - 21202 (2020/09/17)
The development of concise, sustainable, and cost-effective synthesis of aryltetralin lignans, bearing either a fused lactone or cyclic ether, is of significant medicinal importance. Reported is that in the presence of Fukuzumi's acridinium salt under blue LED irradiation, functionalized dicinnamyl ether derivatives are converted into aryltetralin cyclic ether lignans with concurrent generation of three stereocenters in good to high yields with up to 20:1 diastereoselectivity. Oxidation of an alkene to the radical cation is key to the success of this formal Diels–Alder reaction of electronically mismatched diene and dienophile. Applying this methodology, six natural products, aglacin B, aglacin C, sulabiroin A, sulabiroin B, gaultherin C, and isoshonanin, are synthesized in only two to three steps from readily available biomass-derived monolignols. A revised structure is proposed for gaultherin C.
