95257-22-0Relevant articles and documents
Mild C–C Bond Formation via Lewis Acid Catalyzed Oxetane Ring Opening with Soft Carbon Nucleophiles
Huang, Hai,Zhang, Tianyu,Sun, Jianwei
supporting information, p. 2668 - 2673 (2020/12/07)
Mild oxetane opening by soft carbon nucleophiles has been developed for efficient C?C bond formation. In the presence of LiNTf2 or TBSNTf2 as catalyst, silyl ketene acetals were found to be effective nucleophiles to generate a wide range of highly oxygenated molecules, which are key substructure in natural products like polyketides. Furthermore, intramolecular oxetane opening by a styrene-based carbon nucleophile via a Prins-type process was also achieved with Sc(OTf)3 as catalyst, leading to efficient formation of the useful 2,3-dihydrobenzo[b]oxepine skeleton.
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.
3-hydroxyl oxygen heterocyclic butane preparation method of compound
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Paragraph 0032; 0039; 0040, (2016/10/07)
The invention discloses a synthetic method of a 3-hydroxy oxetane compound shown as a formula I. The method provided by the invention employs substituted glycerol I-1 as a raw material, which is subjected to condensation with aldehydes and ketones compounds to obtain a compound I-2; the I-2 is subjected to R2 protection to obtain a compound I-3; the compound I-3 is subjected to removal of aldehydes and ketones protecting groups to obtain a compound I-4; the compound I-4 is subjected to intramolecular cyclization to obtain a compound I-5; and the compound I-5 is subjected to removal of R2 protection to obtain a target compound I. Although the method has a long route, the reaction conditions are mild, and the post treatment and detection are convenient; therefore, the method is suitable for industrialized production.
Catalytic enantioselective intermolecular desymmetrization of 3-substituted oxetanes
Wang, Zhaobin,Chen, Zhilong,Sun, Jianwei
supporting information, p. 6685 - 6688 (2013/07/26)
Wring it out: The title reaction proceeds in the presence of chiral Bronsted acid catalysts. This efficient ring-opening process features low catalyst loading, mild reaction conditions, broad functional group compatibility, high enantioselectivity, and the capability to generate chiral quaternary centers. The highly functionalized desymmetrization products are versatile chiral building blocks in organic synthesis. Copyright
