106988-60-7Relevant academic research and scientific papers
Transannular Ring Expansion in the Acid-Catalyzed Reaction of the Oxirane Derived from Spirocyclopropane-Substituted Bicyclooct-2-ene
Adam, Waldemar,Craemer, Elisabeth,Peters, Eva-Maria,Peters, Karl,Schnering, Hans Georg von
, p. 705 - 712 (2007/10/02)
Spirooct-5-ene-2,1'-cyclopropane> (1), obtained by cycloaddition of 1,3-cyclohexadiene to methylenecyclopropane, was epoxidized to give the exo and endo epoxides 2.The exo epoxide 2 gave with trifluoroacetic acid the 7,9-disubstituted homobrendane 7b (main product) and the 2,6-disubstituted isotwistane 7a (minor product) via transannular ring expansion of the spirocyclopropane substituent with and without skeletal rearrangement of the bicyclic ring system, respectively.No 1,2-trans adducts were observed, as is the case in the reaction of the spiroalkene 1 with arenesulfenyl chloride, which in turn gave no ring-expanded products.The fact that an isomeric mixture of all four possible 1,2-trans adducts 4 were obtained, proves that the spirocyclopropane substituent promotes neither regio- nor stereoselectivity.In contrast, bicyclooct-2-en-5-one proceeded with arenesulfenyl chloride regio- and stereoselectively, leading to (exo-5, endo-6)-6-chloro-5-(p-tolylthio)bicyclooctan-2-one (5a).The stereochemistry of the latter was established by means of X-ray analysis of its sulfoxide derivative 6a.
