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Macrocyclic Ketones (macrocyclic + ketone)
Selected AbstractsDiradical-Promoted Two-Carbon Ring-Expansion Reactions by Thermal Isomerization: Synthesis of Functionalized Macrocyclic KetonesHELVETICA CHIMICA ACTA, Issue 7 2004Georg 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] ChemInform Abstract: Biomimetic Synthesis of Twenty-Four Long-Chained Diketones as Precursors for Muscone and Further Macrocyclic Ketones.CHEMINFORM, Issue 13 2009Yuan Guo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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] Biomimetic Synthesis of Twenty-four Long-chained Diketones as Precursors for Muscone and Further Macrocyclic KetonesCHINESE JOURNAL OF CHEMISTRY, Issue 12 2008Yuan GUO Abstract The one-carbon unit transfer reaction of tetrahydrofolate coenzyme was initiated. Bisbenzimidazolium salts were used as a tetrahydrofolate coenzyme model, and thus the biomimetic synthesis of twenty-four acyclic diketones as precursors for macrocyclic ketones was successfully accomplished by using the addition-hydrolysis reaction of the bisbenzimidazolium salts with alkyl magnesium halide, wherein six diketones have not been reported in literature. Accordingly, a short route to muscone analogues was provided. [source] Diradical-Promoted Two-Carbon Ring-Expansion Reactions by Thermal Isomerization: Synthesis of Functionalized Macrocyclic KetonesHELVETICA CHIMICA ACTA, Issue 7 2004Georg 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] Biomimetic Synthesis of Twenty-four Long-chained Diketones as Precursors for Muscone and Further Macrocyclic KetonesCHINESE JOURNAL OF CHEMISTRY, Issue 12 2008Yuan GUO Abstract The one-carbon unit transfer reaction of tetrahydrofolate coenzyme was initiated. Bisbenzimidazolium salts were used as a tetrahydrofolate coenzyme model, and thus the biomimetic synthesis of twenty-four acyclic diketones as precursors for macrocyclic ketones was successfully accomplished by using the addition-hydrolysis reaction of the bisbenzimidazolium salts with alkyl magnesium halide, wherein six diketones have not been reported in literature. Accordingly, a short route to muscone analogues was provided. [source] | ||||||||||