2612-30-8Relevant academic research and scientific papers
NaBH4-InCl3-mediated one-pot chemo- and stereoselective decarboxylative reduction of α-aza gem-dicarboxylic esters to monoalcohols
Haldar, Pranab,Ray, Jayanta K.
, p. 4341 - 4343 (2005)
(Chemical Equation Presented) The combination of NaBH4 and a catalytic amount of InCl3 provides a one-pot method for chemo- and stereoselective decarboxylative reduction of gem-dicarboxylic esters 1 to monoalcohols 2 in the presence
Umpolung Strategy for Arene C?H Etherification Leading to Functionalized Chromanes Enabled by I(III) N-Ligated Hypervalent Iodine Reagents
Mikhael, Myriam,Guo, Wentao,Tantillo, Dean J.,Wengryniuk, Sarah E.
supporting information, p. 4867 - 4875 (2021/09/14)
The direct formation of aryl C?O bonds via the intramolecular dehydrogenative coupling of a C?H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C?H etherification via an umpoled alcohol cyclization mediated by an I(III) N-HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization-iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O-intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2-shift pathways. (Figure presented.).
MODULATORS OF HSD17B13 AND METHODS OF USE THEREOF
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Paragraph 0436, (2021/01/23)
The disclosure relates to compounds and pharmaceutical compositions capable of modulating the hydroxysteroid 17-beta dehydrogenase (HSD17B) family member proteins including inhibiting the HSD17B member proteins, e.g. HSD17B13. The disclosure further relates to methods of treating liver diseases, disorders, or conditions with the compounds and pharmaceutical compositions disclosed herein, in which the HSD17B family member protein plays a role.
Enantioselective Desymmetrization of 2-Aryl-1,3-propanediols by Direct O-Alkylation with a Rationally Designed Chiral Hemiboronic Acid Catalyst That Mitigates Substrate Conformational Poisoning
Estrada, Carl D.,Ang, Hwee Ting,Vetter, Kim-Marie,Ponich, Ashley A.,Hall, Dennis G.
supporting information, (2021/04/07)
Enantioselective desymmetrization by direct monofunctionalization of prochiral diols is a powerful strategy to prepare valuable synthetic intermediates in high optical purity. Boron acids can activate diols toward nucleophilic additions; however, the design of stable chiral catalysts remains a challenge and highlights the need to identify new chemotypes for this purpose. Herein, the discovery and optimization of a bench-stable chiral 9-hydroxy-9,10-boroxarophenanthrene catalyst is described and applied in the highly enantioselective desymmetrization of 2-aryl-1,3-diols using benzylic electrophiles under operationally simple, ambient conditions. Nucleophilic activation and discrimination of the enantiotopic hydroxy groups on the diol substrate occurs via a defined chairlike six-membered anionic complex with the hemiboronic heterocycle. The optimal binaphthyl-based catalyst 1g features a large aryloxytrityl group to effectively shield one of the two prochiral hydroxy groups on the diol complex, whereas a strategically placed "methyl blocker"on the boroxarophenanthrene unit mitigates the deleterious effect of a competing conformation of the complexed diol that compromised the overall efficiency of the desymmetrization process. This methodology affords monoalkylated products in enantiomeric ratios equal or over 95:5 for a wide range of 1,3-propanediols with various 2-aryl/heteroaryl groups.
A Case Study in Catalyst Generality: Simultaneous, Highly-Enantioselective Br?nsted- And Lewis-Acid Mechanisms in Hydrogen-Bond-Donor Catalyzed Oxetane Openings
Strassfeld, Daniel A.,Algera, Russell F.,Wickens, Zachary K.,Jacobsen, Eric N.
supporting information, p. 9585 - 9594 (2021/07/19)
Generality in asymmetric catalysis can be manifested in dramatic and valuable ways, such as high enantioselectivity across a wide assortment of substrates in a given reaction (broad substrate scope) or as applicability of a given chiral framework across a variety of mechanistically distinct reactions (privileged catalysts). Reactions and catalysts that display such generality hold special utility, because they can be applied broadly and sometimes even predictably in new applications. Despite the great value of such systems, the factors that underlie generality are not well understood. Here, we report a detailed investigation of an asymmetric hydrogen-bond-donor catalyzed oxetane opening with TMSBr that is shown to possess unexpected mechanistic generality. Careful analysis of the role of adventitious protic impurities revealed the participation of competing pathways involving addition of either TMSBr or HBr in the enantiodetermining, ring-opening event. The optimal catalyst induces high enantioselectivity in both pathways, thereby achieving precise stereocontrol in fundamentally different mechanisms under the same conditions and with the same chiral framework. The basis for that generality is analyzed using a combination of experimental and computational methods, which indicate that proximally localized catalyst components cooperatively stabilize and precisely orient dipolar enantiodetermining transition states in both pathways. Generality across different mechanisms is rarely considered in catalyst discovery efforts, but we suggest that it may play a role in the identification of so-called privileged catalysts.
Highly Enantioselective, Hydrogen-Bond-Donor Catalyzed Additions to Oxetanes
Strassfeld, Daniel A.,Wickens, Zachary K.,Picazo, Elias,Jacobsen, Eric N.
supporting information, p. 9175 - 9180 (2020/07/13)
A precisely designed chiral squaramide derivative is shown to promote the highly enantioselective addition of trimethylsilyl bromide (TMSBr) to a broad variety of 3-substituted and 3,3-disubstituted oxetanes. The reaction provides direct and general access to synthetically valuable 1,3-bromohydrin building blocks from easily accessed achiral precursors. The products are readily elaborated both by nucleophilic substitution and through transition-metal-catalyzed cross-coupling reactions. The enantioselective catalytic oxetane ring opening was employed as part of a three-step, gram-scale synthesis of pretomanid, a recently approved medication for the treatment of multidrug-resistant tuberculosis. Heavy-atom kinetic isotope effect (KIE) studies are consistent with enantiodetermining delivery of bromide from the H-bond-donor (HBD) catalyst to the activated oxetane. While the nucleophilicity of the bromide ion is expected to be attenuated by association to the HBD, overall rate acceleration is achieved by enhancement of Lewis acidity of the TMSBr reagent through anion abstraction.
An aryne triggered ring-opening fluorination of cyclic thioethers with potassium fluoride
Fan, Rong,Liu, Binbin,Zheng, Tianyu,Xu, Kun,Tan, Chen,Zeng, Tianlong,Su, Shuaisong,Tan, Jiajing
supporting information, p. 7081 - 7084 (2018/07/05)
Herein, we report an aryne triggered ring-opening fluorination protocol of a great variety of saturated sulfur heterocycles. A key factor for the success is the identification of a suitable mediator. Compared to previous methods, this transition-metal free protocol employs low-cost potassium fluoride as the fluorine source. The operational simplicity and mild reaction conditions allow for the rapid synthesis of a wide range of aliphatic fluoride compounds in good yields.
Biocatalytic Desymmetrization of Prochiral 3-Aryl and 3-Arylmethyl Glutaramides: Different Remote Substituent Effect on Catalytic Efficiency and Enantioselectivity
Ao, Yu-Fei,Zhang, Li-Bin,Wang, Qi-Qiang,Wang, De-Xian,Wang, Mei-Xiang
supporting information, p. 4594 - 4603 (2018/10/31)
Catalyzed by an amidase-containing Rhodococcus erythropolis AJ270 microbial whole cell catalyst in neutral phosphate buffer at 30 °C, desymmetric hydrolysis of a series of prochiral 3-aryl and 3-arylmethylglutaramides efficiently afforded 3-substituted glutaric acid monoamides in up to 95% yield and >99.5% ee. Even far away from the reaction site, the substituents on the aryl still have a significant effect on the catalytic activity and enantioselectivity and different remote substituent effect was observed for the two types of substrates. The synthetic application of biocatalytic desymmetrization was demonstrated by the facile transformation of the obtained enantiopure (R)-3-substituted 4-carbamoylbutanoic acid products to chiral dihydroquinolinone and δ-lactone compounds. (Figure presented.).
Dual Rh?Ru Catalysts for Reductive Hydroformylation of Olefins to Alcohols
Rodrigues, Fábio M. S.,Kucmierczyk, Peter K.,Pineiro, Marta,Jackstell, Ralf,Franke, Robert,Pereira, Mariette M.,Beller, Matthias
, p. 2310 - 2314 (2018/07/31)
An active and selective dual catalytic system to promote domino hydroformylation–reduction reactions is described. Apart from terminal, di- and trisubstituted olefins, for the first time the less active internal C?C double bond of tetrasubstituted alkenes can also be utilized. As an example, 2,3-dimethylbut-2-ene is converted into the corresponding n-alcohol with high yield (90 %) as well as regio- and chemoselectivity (>97 %). Key for this development is the use of a combination of Rh complexes with bulky monophosphite ligands and the Ru-based Shvo's complex. A variety of aromatic and aliphatic alkenes can be directly used to obtain mainly linear alcohols.
ELECTROCHROMIC SINGLE AND TWO-CORE VIOLOGENS AND OPTICAL ARTICLES CONTAINING THEM
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Paragraph 0110-0112, (2016/09/12)
The present invention relates to a group of novel electrochromic materials. More specifically, it relates to electrochromic materials based on either single or two-core viologen systems and the use of these viologen systems as a variable transmittance medium for the manufacture of an optical article, such as an ophthalmic lens.
