carbon chain with carbocyclic (phenyl and cyclopropane) and heterocyclic (epoxide and dioxolane) moieties were prepared and their cyclizations in the presence of bis(collidine)iodonium(I) and -bromonium(I) hexafluorophosphates as electrophiles were studied. Oxocanes were obtained in modest to good yields when a rigid cyclic moiety (cyclopropane or phenyl) was present in the chain, while yields of cyclizations
Evaluation of <i>e</i><i>xo</i>-<i>e</i><i>ndo</i> Ratios in the Halolactonization of ω-Unsaturated Acids
作者:Marie-Claude Roux、Renée Paugam、Gérard Rousseau
DOI:10.1021/jo0017234
日期:2001.6.1
competition between electronic and stericeffects. These latter were developed by transannular interactions (for the acid chain lengths 8-11) and/or the conformations adopted by the chains (for the acid chain lengths > or = 14,) which disfavored the formation of the exo lactones. The larger proportion of endo lactones observed with the bromo reagent compared to the iodo reagent seemed due to electronic factors