نتایج جستجو برای: stereoselective
تعداد نتایج: 4707 فیلتر نتایج به سال:
Stereoselective photodimerization of coumarin and its derivatives in supra-molecular systems is reviewed. The enantioselective photodimerization of coumarin and thiocoumarin in inclusion crystals with optically active host compounds is also described.
The regioselective and enantiospecific rhodium-catalyzed allylic amination of secondary allylic carbonates with N3-benzoyl thymine in conjunction with a stereoselective free radical cyclization provides a convenient method for the construction of a new conformationally rigid nucleoside.
A (bromodifluoromethyl)alkyne has been deployed in a stereoselective route to difluorinated aldonic acid analogues, in which a Sharpless asymmetric dihydroxylation reaction and diastereoisomer separation set the stage for phenyl group oxidation.
[reaction: see text] 4-Deoxypentenosides, which are readily derived from D-sugars, resemble glycals in structure and reactivity and can undergo stereoselective epoxidation and S(N)2 nucleophilic addition to produce L-sugars in pyranosidic form.
Stereoselective palladium-catalyzed Kumada-Corriu reactions of functionalized alkenyl halides and a variety of Grignard reagents, including those bearing β-hydrogen atoms and sensitive functional groups, can be carried out at room temperature using a new combination of reagents.
Bromination of an isolated double bond followed by aminocyclization furnishes a highly stereoselective protocol for the intramolecular formation of pyrrolidine and piperidine ring containing subunits that are presented in numerous biologically active natural products.
A chiral 1,8-diacridylnaphthalene-derived fluorosensor exhibiting a C(2)-symmetric cleft designed for stereoselective interactions with hydrogen bond donors has been used for the determination of both concentration and enantiomeric composition of carboxylic acids and amino acid derivatives.
The synthesis of capsanthin 1 and capsorubin 2 was accomplished via the C(15)-cyclopentyl ketone 6 prepared by Lewis acid-promoted regio- and stereoselective rearrangement of the epoxy dienal 5.
A concise synthesis of the marine alkaloids (-)-lepadins A-C from a phenylglycinol-derived tricyclic lactam is reported. Key steps from the stereochemical standpoint involve stereoselective cyclocondensation, double bond hydrogenation, oxazolidine opening, hydroboration-oxidation, and Horner-Wadsworth-Emmons reactions.
Angularly substituted trans-fused hydroindanes are now accessible by the direct and convergent union of trimethylsilyl (TMS)-alkynes with 4-hydroxy-1,6-enynes by a process that forges three C-C bonds, one C-H bond, and two new stereocenters. The annulation is proposed to proceed by initial formation of a Ti-alkyne complex (with a TMS-alkyne) followed by regioselective alkoxide-directed coupling...
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