Metalated Nitriles: SNi and SNi′ Installation of Contiguous Quaternary-Tertiary and Quaternary-Quaternary Centers
نویسندگان
چکیده
منابع مشابه
Highly diastereoselective and enantiospecific allylation of ketones and imines using borinic esters: contiguous quaternary stereogenic centers.
3,3-Disubstituted allylic boronic esters are not sufficiently reactive to react with ketones and imines. However, they can be converted into the corresponding borinic esters by the sequential addition of nBuLi and TFAA. These reactive intermediates possess the perfect balance between reactivity and configurational stability. Their enhanced reactivity allows the highly selective allylation of bo...
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The preparation of the crystalline amide 2 is reported. Conjugate addition to 2 proceeded with the expected high diastereocontrol to give 3. This set the stage for subsequent intramolecular alkylidene C-H insertion to give, after ozonolysis and aldol condensation, (-)-mesembrine 1. Amide 2 should be a useful chiron for the enantioselective construction of cyclic quaternary centers.
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An efficient and diastereoselective (CDC)–Rh-catalyzed hydroalkylation of dienes with 1,3-oxazol-5(4H)ones is reported. Aryl and alkyl substituted dienes are converted to a,a-substituted oxazolones (24 examples) by the formation of N-substituted quaternary carbon stereogenic centers in good yields (up to 96%) and with high diastereoselectivity (>20 : 1 dr). The reaction is tolerant of a range o...
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The creation of quaternary stereogenic centers with high enantioselectivity is challenging, in part, because of the high steric repulsion between the substituents on the carbon center that is generated during construction. Nevertheless, significant progress has been made towards this goal in recent years, even in conformationally flexible acyclic systems. However, whilst in many cases high e.r....
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Human transthyretin (TTR) can be transformed into amyloid fibrils by partial acid denaturation to yield a monomeric amyloidogenic intermediate that self-associates into amyloid through quaternary structural intermediates, which are identified by sedimentation velocity methods. The monomeric amyloidogenic intermediate has substantial beta-sheet structure with a nonnative but intact tertiary stru...
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ژورنال
عنوان ژورنال: Chemistry - A European Journal
سال: 2013
ISSN: 0947-6539
DOI: 10.1002/chem.201301046