5689-04-3Relevant academic research and scientific papers
On Baldwin's Kinetic Barrier Against 5-(Enol-endo)-exo-trigonal Closures: a Comparison of Ionic and Analogous Radical Reactions, and a New Synthesis of Cyclopentanones
Clive, Derrick L. J.,Cheshire, David R.
, p. 1520 - 1523 (2007/10/02)
The kinetic barrier that impedes ionic 5-(enol-endo)-exo-trigonal closures does not play such a dominant role in the case of α-oxo radicals (17); these radicals cyclize directly to cyclopentanones in a process that constitutes a synthetic method for conve
Ring Expansion of Cyclobutanones to Cyclopentanones via α-Lithioalkyl Aryl Sulfoxides and Selenoxides
Gadwood, Robert C.,Mallick, Ishwar M.,DeWinter, Amy J.
, p. 774 - 782 (2007/10/02)
Reaction of α-lithioalkyl 2-chlorophenyl sulfoxides (prepared from the corresponding sulfoxides and LDA) with cyclobutanones affords adducts which undergo ring expansion to cyclopentanones upon treatment with potassium hydride.This reaction only works for cyclobutanones substituted at C2 with at least one phenyl or alkenyl group (type I and type II cyclobutanones).Cyclobutanones substituted at C2 with at least one alkyl group (type III and type IV cyclobutanones) undergo similar ring expansion upon treatment with α-lithioalkylphenyl selenoxides followed by direct thermolysis of the adducts.With both the sulfoxide and selenoxide reagents, the carbon atom inserted into the cyclobutanone can be unsubstituted, monosubstituted, or disubstituted.The ring expansions of 17 different cyclobutanones to 29 different cyclopentanones are presented.
Cyclopentanone Synthesis by Intramolecular Carbon-Hydrogen Insertion of Diazo Ketones. A Diterpene-to-Steroid Skeleton Conversion
Wenkert, Ernest,Davis, Linda L.,Mylari, Banavara L.,Solomon, Mary F.,Silva, Roberto R. da,et al.
, p. 3242 - 3247 (2007/10/02)
Intramolecular carbon-hydrogen insertion on cupric sulfate assisted decomposition of diazomethyl ketones derived from four 1-methylcycloalkanecarboxylic acids and (hexahydrophenyl)acetic, homopivalic, and enanthic acids is shown to yield mostly cyclopentanones.The yields are appreciable in the conformationally favorable cases, and insertion in the solvent cyclohexane can be avoided by the use of Freon TF as the solvent.The conversion of a primaradienic diterpene into a 14-iso-16-androstanone derivative shows the power of the new method of cyclopentanone synthesis.
