Sequenced Reactions with Samarium(II) Iodide. Tandem Intramolecular Nucleophilic Acyl Substitution/Intramolecular Barbier Cyclizations
摘要:
Samarium(II) iodide has been employed to promote a tandem intramolecular nucleophilic acyl substitution/intramolecular Barbier cyclization sequence, generating bicyclic and tricyclic ring systems in excellent yield and high diastereoselectivity. Additionally, a highly versatile ring expansion-cyclization sequence allows entry into several different naturally occurring tricyclic ring systems containing seven- and eight-membered rings.
Sequenced Reactions with Samarium(II) Iodide. Tandem Intramolecular Nucleophilic Acyl Substitution/Intramolecular Barbier Cyclizations
作者:Gary A. Molander、Christina R. Harris
DOI:10.1021/ja00118a007
日期:1995.4
Samarium(II) iodide has been employed to promote a tandem intramolecular nucleophilic acyl substitution/intramolecular Barbier cyclization sequence, generating bicyclic and tricyclic ring systems in excellent yield and high diastereoselectivity. Additionally, a highly versatile ring expansion-cyclization sequence allows entry into several different naturally occurring tricyclic ring systems containing seven- and eight-membered rings.
Photochemical and Thermal Ring-Contraction of Cyclic Hydroxamic Acid Derivatives
can undergo a thermal ring contraction after an in situ triflation. High yields of ring-contraction products are obtained with DBU when the migrating carbon is a methylene, while best results are obtained with Et3N for the migration of quaternary carbons. In some cases, the regiochemical outcome of the reaction can be controlled by changing the base. This novel thermalrearrangement complements a similar