Exploratory study on α-metallo selenones: original syntheses of oxaspiropentanes
作者:A. Krief、W. Dumont、J.L. Laboureur
DOI:10.1016/0040-4039(88)85138-4
日期:1988.1
Oxaspiropentanes have been obtained from α-metallocyclopropyl phenyl selenones and carbonyl compounds and on reaction of a base with β-hydroxyalkyl cyclopropyl selenones. The original reactivity of other β-hydroxyalkyl selenones is also disclosed.
Catalytic and Regioselective Ring Expansion of Arylcyclobutanones with Trimethylsilyldiazomethane. Ligand-Dependent Entry to β-Ketosilane or Enolsilane Adducts
作者:Jennifer A. Dabrowski、David C. Moebius、Andrew J. Wommack、Anne F. Kornahrens、Jason S. Kingsbury
DOI:10.1021/ol101136a
日期:2010.8.20
Divergent reactivity is uncovered in the homologation of arylcyclobutanones with trimethylsilyldiazomethane. With Sc(OTf)(3) as catalyst, enolsilanes are obtained with a high preference for methylene migration. By contrast, Sc(hfac)(3) gives beta-ketosilanes with both regio- and diastereocontrol. Each adduct affords the cyclopentanone upon hydrolysis.
Oxidative Ring Expansion of Cyclobutanols: Access to Functionalized 1,2-Dioxanes
an oxidative ring expansion with Co(acac)2 and triplet oxygen to give 1,2-dioxanols. The formation of an alkoxy radical drives the regioselectivecleavage of the ring on the more substituted side before insertion of molecular oxygen. The reaction is particularly effective on secondary cyclobutanols but works also on certain tertiary alcohols. Further substitution with neutral nucleophiles under catalytic