Enamine-Iminium Ion Nazarov Cyclization of α-Ketoenones
نویسندگان
چکیده
منابع مشابه
Catalytic formal Homo-Nazarov cyclization.
The first catalytic method for the cyclization of vinyl-cyclopropyl ketones (formal homo-Nazarov reaction) is reported. Starting from activated cyclopropanes, heterocyclic, and carbocyclic compounds were obtained under mild conditions using Brønsted acid catalysts. Preliminary investigation of the reaction mechanism indicated a stepwise process.
متن کاملConquering the Challenges of the Nazarov Cyclization
One of the most powerful synthetic transformations with the ability to stereospecifically create new carbon-carbon bonds by simple orbital reorganization are electrocyclic reactions. One of the most recognized electrocyclic reactions is known as Nazarov cyclization. This reaction involves the conversion of divinyl ketones to cyclopentenones by activation with a Brønsted or Lewis acid. It was or...
متن کاملAssembly of spirooxindole derivatives via organocatalytic iminium-enamine cascade reactions.
The assembly of complex spirocyclopentaneoxindoles via a novel organocatalytic iminium-enamine cascade process is reported. Reactions between 3-substituted oxindoles and α,β-unsaturated aldehydes catalyzed by second generation prolinol ethers provided the desired products in high yield with excellent levels of enantioselectivity in a single step.
متن کاملStereoselectivity in N-Iminium Ion Cyclization: Development of an Efficient Synthesis of (±)-Cephalotaxine.
A stereoselective N-iminium ion cyclization with allylsilane to construct vicinal quaternary-tertiary carbon centers was developed for the concise synthesis of (±)-cephalotaxine. The current strategy features a TiCl4-promoted cyclization and ring-closure metathesis to furnish the spiro-ring system. The stereochemical outcome in the N-acyliminium ion cyclization was rationalized by the stereoele...
متن کاملExperimental and quantum-mechanical investigation of the vinylsilane-iminium ion cyclization.
A vinylsilane-ketiminium ion cyclization involving iminium species derived from amines 6 and 7 was investigated experimentally as a possible approach to some biologically interesting 1-azaspirocycles. However, even under conditions of microwave irradiation at high temperatures no such cyclization was observed whereas (in line with previous results) the corresponding vinylsilane-aldiminium ion c...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Organic Letters
سال: 2009
ISSN: 1523-7060,1523-7052
DOI: 10.1021/ol9025765