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DOI: 10.1055/s-1994-25673
α-Oxoketenes - Preparation and Chemistry
Publikationsverlauf
Publikationsdatum:
25. April 2002 (online)
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This review describes the methods of generation of α-oxoketenes and their use in synthesis. While the ketenes are often generated in situ without direct proof for their existence, methods used for their direct observation are also emphasized. The most important classes of precursor molecules are 2-diazo-1, 3-diketones,1,3-dioxin-4-ones, 2,3-dihydrofuran-2,3-diones, and β-ketoacid derivatives. Synthetically useful reactions are nucleophilic additions to give carboxylic acid derivatives which can be subjected to further functional group manipulation, [2 + 2] cycloadditions to give four-membered rings, and [2 + 4] cycloaddition chemistry with a wide variety of double-and triple-bonded dienophiles, resulting in numerous six-membered heterocyclic ring systems. 1. Introduction 2. Generation and Direct Observation 2.1. From Diazo Compounds 2.2. From 1,3-Dioxinones 2.3. From Furan-2,3-diones 2.4. From Carboxylic Acid Derivatives 2.5. From Alkynol Derivatives 2.6. Other Methods 3. Reactions 3.1. With Nucleophiles 3.1.1. Intermolecular 3.1.1.1. Synthesis of β-Ketoacid Derivatives 3.1.1.2. Synthesis of Heterocycles 3.1.1.3. Mechanistic Aspects 3.1.2. Intramolecular 3.2. Cycloaddition Reactions 3.2.1. [2 + 4] Cycloadditions 3.2.1.1. Dimerization and Oligomerization 3.2.1.2. [2 + 4] Cycloaddition Reactions with X = Y and C ≡ X Systems 3.2.2. 1,3-Dipolar [2 + 4] Cycloaddition 3.2.3. [2 + 2] Cycloadditions 3.3. Rearrangements 3.3.1. Electrocyclic Reactions and CO Elimination 3.3.2. Tandem Cyclizations 3.3.3. Ketoketene-Ketoketene Interconversion