نتایج جستجو برای: desymmetrization
تعداد نتایج: 310 فیلتر نتایج به سال:
A very short and efficient synthesis of the important drug candidate telaprevir, featuring a biocatalytic desymmetrization and two multicomponent reactions as the key steps, is presented. The classical issue of lack of stereoselectivity in Ugi- and Passerini-type reactions is circumvented. The atom economic and convergent nature of the synthetic strategy require only very limited use of protect...
Described herein is a highly enantioselective synthesis of fused piperidine and pyrrolidine derivatives with all-carbon stereogenic centers. The enantioselective reductive amination from C(s)-symmetric 1,3-dione derivatives proceeded in a highly stereoselective manner by taking advantage of the desymmetrization approach to afford fused heterocycles with contiguous stereogenic centers in good to...
An enantioselective desymmetrization of prochiral 1,3-dinitropropanes has been developed which proceeds via enantiogroup differentiating organocatalytic allylic alkylation. Densely functionalized products with two vicinal stereocenters were obtained generally with good to excellent diastereoselectivity (up to >20 : 1 dr) and superb enantioselectivity (up to >99 : 1 er).
A highly enantioselective method for desymmetrization of meso-epoxides using thiols is reported. This is the first example of epoxide activation achieved using metal BINOL phosphates. The reaction has a broad scope in terms of epoxide substrates and aromatic thiol nucleophiles. The resulting β-hydroxyl sulfides are obtained in excellent yield and enantioselectivity.
The LFA-1 inhibitor and leukocyte adhesion suppressor BIRT-377 was prepared in high enantiomeric excess by desymmetrization of dimethyl 2-p-bromobenzyl-2-methylmalonate, followed by condensation of the resulting carboxylic acid with 3,5-dichloroaniline, saponification of the remaining ester and Curtius rearrangement as the key steps. When Curtius rearrangement preceded the condensation step, (e...
Abstract We report a Brønsted acid catalyzed enantioselective silylation of biaryl diols with an allylsilane as silicon source. This process enables facile access to enantioenriched silyl ethers axial stereogenicity. A control experiment supports mechanism proceeding by desymmetrization followed kinetic resolution.
Consecutive intramolecular desymmetrization and kinetic resolution of 2-substituted N-phenoxycarbonylserinols have been achieved in one-pot by a single chiral catalyst, bisox)-CuCl2, to form oxazolidinones with remarkable enantioselectivities (94-99% ee) as tert-alkylamine building blocks. The process culminates in a dual-function of the chiral catalyst.
A highly enantioselective (>95% ee) strategy to affect the desymmetrization of a maleimide has been performed by temporary attachment to an anthracene template followed by asymmetric reduction with an oxazaborolidine catalyst. A stereoablative over-reduction process was partially responsible for the high levels of enantioselectivity. Exemplification of the strategy by stereoselective functional...
Monofunctionalization of trehalose, a widely-found symmetric plant disaccharide, was studied in a microreactor to give valuable kinetic insights that have allowed improvements in desymmetrization yields and the development of a reaction sequence for large scale monofunctionalizations that allow access to probes of trehalose's biological function.
Enantioselective reductive desymmetrization of glutarimides has been achieved employing an oxazaborolidine catalyst derived from cis-1-amino-indan-2-ol. The reaction was found to proceed through a stereoablative process that upgraded the enantioselectivity of an intermediate hydroxy-lactam. The reaction was generally tolerant of a number of substituents in the 4-position, giving enantiomeric ex...
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