نتایج جستجو برای: stereoselective
تعداد نتایج: 4707 فیلتر نتایج به سال:
Racemic R,S-salbutamol is taken to relieve bronchial constriction. Only the R-enantiomer has bronchodilating properties. The S-enantiomer has been proposed to cause in vitro bronchial hyperreactivity in guinea-pigs. Stereoselective elimination of salbutamol has been shown, with S-salbutamol being eliminated at a slower rate than R-salbutamol. This study questioned whether rates of stereoselecti...
We report of a concise synthesis (R)-sitagliptin monophosphate – drug predominantly applied in the treatment type 2 diabetes. Utilizing our recently developed RhI-catalyzed hydroamination allenes for stereoselective construction inherent chiral amino function, new approach to on 3.5 mmol scale was established.
This chapter offers a general review of the evolvement of methods for the stereoselective synthesis of Z-alkenes, with a focus on the development of catalytic systems towards this goal in recent years.
A short stereoselective synthesis of (+)-(6R,2'S)-cryptocaryalactone was successfully completed. Key steps included the application of Carreira's asymmetric alkynylation reaction to form a propargylic alcohol and subsequently lactone formation using the powerful ring-closing metathesis reaction.
Starting from (S)-tryptophanol, a formal synthesis of ent-rhynchophylline and ent-isorhynchophylline, involving stereoselective cyclocondensation, spirocyclization, and alkylation reactions, and the final adjustment of the oxidation level at the oxindole and piperidine moieties, is reported.
Allenynes having malonate-based tethers reacted with arylboronic acids in the presence of a rhodium(I) catalyst to sequentially form three carbon-carbon bonds, and arylated bicyclic skeletons were constructed in a stereoselective manner.
[reaction: see text] An enantiospecific synthesis of a coccinellied alkaloid, (-)-adalinine, was established starting from (S)-(-)-pyroglutamic acid, where a stereoselective Michael addition and a samarium iodide-promoted regioselective carbon-nitrogen bond cleavage reaction were involved as the key reactions.
Highly stereoselective alkylative and arylative cyclization reactions of allenyl-aldehydes and -ketones with organozinc reagents occur efficiently in the presence of catalytic Ni(COD)2 to afford cis-fused homoallylic cyclopentanols.
A rhodium(I)/dppe catalyst promoted dimerization of monosubstituted allenes in a stereoselective manner to give cross-conjugated trienes, which are different from those obtained by a palladium catalyst.
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