Brønsted Acid-Promoted Intramolecular Carbocyclization of Alkynals Leading to Cyclic Enones
摘要:
TFA-promoted exo carbocyclizations of nonterminal 7-alkynals gave good to excellent yields of seven-membered cycloalkenones, a medium-sized functionalized ring present in natural products with relevant pharmacological properties. Nonterminal 5- and 6-alkynals also gave very good yields of the corresponding exo cyclopentenones and cyclohexenones. On the other hand, terminal 5-alkynals gave endo carbocyclizations to cyclohexenones. These carbocyclizations can be considered as tandem alkyne hydration/aldol condensation processes.
A Novel Method of Annulation through α,β-Epoxy Sulfoxides with the Aid of Intramolecular Radical Cyclization
作者:Tsuyoshi Satoh、Masayuki Itoh、Koji Yamakawa
DOI:10.1246/cl.1987.1949
日期:1987.10.5
A novel method of annulation was realized from ketones through α,β-epoxy sulfoxides with the aid of endo-type intramolecular radical cyclization. In these reactions 1-chloroalkyl phenyl sulfoxides having phenylseleno group on an end of the alkyl group acted as synthons of the annulation.