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Ring-Expansion Reaction (ring-expansion + reaction)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Palladium-Catalyzed Ring-Expansion Reaction of Indoles with Alkynes: From Indoles to Tetrahydroquinoline Derivatives Under Mild Reaction Conditions,

ANGEWANDTE CHEMIE, Issue 24 2010
Zhuangzhi Shi
Ausbaufähiges Indol: Die hoch selektiv mit O2 als Oxidationsmittel und unter doppelter C-H-Aktivierung verlaufende Titelreaktion öffnet einen neuen Zugang zu polysubstituierten 4,5-Dihydrocyclopenta[c]chinolinen (siehe Schema). Außerdem wurden Einblicke in den Mechanismus dieser Ringerweiterung erhalten. [source]

ChemInform Abstract: A Pd(II)-Catalyzed Ring-Expansion Reaction of Cyclic 2-Azidoalcohol Derivatives: Synthesis of Azaheterocycles.

CHEMINFORM, Issue 4 2010
Shunsuke Chiba
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Diastereoselective Ring-Expansion Reaction of Methanochromanone with Aldehydes: Formation of trans-Fused Tetrahydrofuro[2,3-b][1]benzopyranones and Their Isomerization.

CHEMINFORM, Issue 42 2001
Yoshiaki Sugita
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Synthesis of Trisubstituted 4-Oxepanones by the Lewis Acid Promoted Three-Component Ring-Expansion Reaction of Cyclopropapyranones, Silyl Enolates, and Glyoxylates.

CHEMINFORM, Issue 36 2001
Yoshiaki Sugita
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Diradical-Promoted Two-Carbon Ring-Expansion Reactions by Thermal Isomerization: Synthesis of Functionalized Macrocyclic Ketones

HELVETICA CHIMICA ACTA, Issue 7 2004
Georg Rüedi
A new method for the smooth and highly efficient preparation of functionalized macrocyclic ketones has been developed. Pyrolysis of medium- and large-ring 3-vinylcycloalkanones by dynamic gas-phase thermo-isomerization (DGPTI) at 600,630° yielded, under insertion of a previously attached vinyl side chain by means of a 1,3-C shift, the corresponding ,,, -unsaturated cycloalkanones. The yield of the two-carbon ring-expanded ketones greatly depended on the relative ring strains of substrate and product (5,87%, cf. Table,5). The formation of minor amounts of one-carbon ring-expanded cycloalkenes (<10%) can be ascribed to a subsequent decarbonylation step. A reaction mechanism involving initial cleavage of the weakest single bond in the molecule has been established (cf. Scheme,6). Recombination within the generated diradical intermediate in terminal vinylogous position led to the observed products, while reclosure gave recovered starting material. Substituents on the vinyl moiety were transferred locospecifically into the ring-expanded products. An isopropenyl group did not significantly affect the isomerization process, whereas substrates bearing a prop-1-enyl group in , -position enabled competing intramolecular H-abstraction reactions, leading to acyclic dienones (cf. Schemes,9,11). DGPTI of the 13-membered analogue directly yielded 4-muscenone, which, upon hydrogenation, led to the valuable musk odorant (±)-muscone. Increasing the steric hindrance on the vinyl moiety gave rise to diminishing amounts of the desired ,,, -unsaturated cycloalkanones. This novel two-carbon ring-expansion protocol was also successfully applied to 3-ethynylcycloalkanones, giving rise to the corresponding ring-expanded cyclic allenes (cf. Scheme,13). [source]