Preparation of spiro[indole-3,5′-isoxazoles] via Grignard conjugate addition/spirocyclization sequence
نویسندگان
چکیده
منابع مشابه
Catalytic asymmetric conjugate addition of Grignard reagents to chromones.
A highly regio- and enantioselective copper catalysed direct conjugate addition of Grignard reagents to chromones has been developed taking advantage of the reduced reactivity of the resulting magnesium enolates. This methodology tolerates a broad scope of alkyl Grignards including secondary alkyl magnesium reagents as well as functionalised chromones.
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An efficient enantioselective synthesis of lactones was developed based on the catalytic asymmetric conjugate addition (ACA) of alkyl Grignard reagents to pyranones. The use of 2H-pyran-2-one for the first time in the ACA with Grignard reagents allows for a variety of further transformations to access highly versatile building blocks such as β-alkyl substituted aldehydes or β-bromo-γ-alkyl subs...
متن کاملPreparation and rearrangement of N-vinyl nitrones: synthesis of spiroisoxazolines and fluorene-tethered isoxazoles.
N-Vinyl nitrones derived from fluorenone have been prepared via a copper-mediated coupling between fluorenone oxime and vinyl boronic acids. These compounds undergo subsequent rearrangement and addition reactions that are distinct from the traditional [3 + 2] cycloaddition reactivity of nitrones. Thermal rearrangements of fluorenone N-vinyl nitrones give spiroisoxazolines, while treatment with ...
متن کاملCopper-catalyzed asymmetric conjugate addition of Grignard reagents to cyclic enones.
It is no longer necessary to use dialkylzinc reagents to obtain enantioselectivities >95% in the copper-catalyzed asymmetric conjugate addition of organometallic compounds to cyclic enones. We now report how this can be accomplished by using inexpensive and readily available Grignard reagents. Screening of bidentate ligands provided outstanding results with copper complexes of commercially avai...
متن کاملOne-pot synthesis of highly functionalized pyridines via a rhodium carbenoid induced ring expansion of isoxazoles.
A concise one-pot synthesis of highly functionalized pyridines has been developed. The first step in the reaction sequence is the formal insertion of rhodium vinylcarbenoids across the N-O bond of isoxazoles. Upon heating, the insertion products undergo a rearrangement to give 1,4-dihydropyridines. DDQ oxidation then affords the corresponding pyridines in 31-84% yield. The process has proven ge...
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ژورنال
عنوان ژورنال: RSC Advances
سال: 2021
ISSN: 2046-2069
DOI: 10.1039/d0ra10219a