نتایج جستجو برای: chiral pyrrolidines
تعداد نتایج: 37647 فیلتر نتایج به سال:
In the present paper, the expressions for scalar and vector potentials in lossless isotropic chiral media are analyzed. Propagating eigenvalues of these potentials are then obtained. Furthermore by decomposition of sources and fields in a chiral medium, we introduce the auxiliary right-and left-handed potentials and find the associated fields. These potentials are used to solve the problem of a...
در این پایان نامه با هدف نهایی تعیین بار فرمیونی سالیتونها، جفت شدگی میدانهای فرمیونی و سالیتونی در نظر گرفته شده است . در فصل اول مفاهیم سالیتون و امواج سالیتاری مورد بررسی قرار گرفته، و در این راستا چنین امواجی با مثالهایی در 1+1 و 1+2 بعد توصیف گردیده اند. در فصل دوم قطبیده شدن خلاء فرمیون (vacuum polarization: vp) در حضور میدان سالیتونی مورد بررسی قرار گرفته. در این زمینه در سال 1994 گوشه و...
A zinc-ProPhenol-catalyzed direct asymmetric aldol reaction between glycine Schiff bases and aldehydes is reported. The design and synthesis of new ProPhenol ligands bearing 2,5-trans-disubstituted pyrrolidines was essential for the success of this process. The transformation operates at room temperature and affords syn β-hydroxy-α-amino esters in high yields with good to excellent levels of di...
An efficient one-pot nitro-Mannich/hydroamination cascade reaction for the synthesis of substituted pyrrolidines bearing three stereocentres is reported. Proceeding under the control of a combination of base and gold(I) catalysts, the cascade reaction affords the pyrrolidine products in high yields with good to excellent diastereoselectivities.
2,2,5-Trisubstituted pyrrolidines are available from allylic pyroglutamates by Ireland-Claisen ester rearrangement followed by Eschenmoser sulfide contraction and reduction in a highly diastereoselective and efficient sequence. Some of the products from this sequence exhibit activity against S. aureus, but are much less active against E. coli.
Pin the amine on the gamma: A new method has been developed for the γ-addition of nitrogen nucleophiles to γ-substituted alkynoates or allenoates through intra- and intermolecular processes that are catalyzed by spirophosphine 1. An asymmetric version of this reaction affords enantioenriched pyrrolidines, indolines, and γ-amino-α,β-unsaturated carbonyl compounds.
A common approach in resolving enantiomers of chiral basic drugs by capillary electrophoresis (CE) is to use cyclodextrins (especially their anionic derivatives) as chiral selector in the acidic buffer (pH ≤ 3) in normal or reversed (carrier) mode. Then, some organic modifiers are added to the buffer solution if the resolution is not satisfactory. In case of cetirizine (CTN), applying the same ...
Palladium(II)-catalyzed aerobic oxidative cyclization of alkenes with tethered tert-butanesulfinamides furnishes enantiopure 2,5-disubstituted pyrrolidines, originating from readily available and easily diversified starting materials. These reactions are the first reported examples of metal-catalyzed addition of sulfinamide nucleophiles to alkenes.
This review highlights the biological importance of many polysubstituted nitro-prolines and -pyrrolidines. Their preparation using asymmetric 1,3-dipolar cycloadditions of azomethine ylides with nitroalkenes using diastereoselective and enantioselective strategies is described remarking the scope and main features of each one.
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