Synthesis of Cyclopropyl Ethers and Cyclopropanols by Carbene Transfer – Acetolysis of Cyclopropyl p-Toluenesulfonates

Authors

  • Prof. Dr. U. Schöllkopf

    Corresponding author
    1. Organisch-Chemisches Institut der Universität, 34 Göttingen, Windausweg 2 (Germany)
    • Organisch-Chemisches Institut der Universität, 34 Göttingen, Windausweg 2 (Germany)
    Search for more papers by this author

  • Based on a Plenary Lecture to the Symposium on the Chemistry of Small Rings (Louvain, Belgium, September 12–15, 1967).

Abstract

The reaction of chloromethyl phenyl ether with butyllithium in olefins yields phenoxy-cyclopropanes. 1-Chloro-1-phenoxycyclopropanes can be prepared in a similar manner, though the yields are poor. Alkoxycyclopropanes are formed when dichloromethyl alkyl ethers are treated with methyllithium/lithium iodide in the presence of olefins. Cyclopropanols can be obtained in good yields by reaction of (β-chloroethoxy)cyclopropanes either with butyl- or ethyllithium or with bases. – As was shown by acetolysis experiments with cyclopropyl p-toluenesulfonates having a known steric configuration, the rearrangement of a cyclopropyl derivative into an allyl cation proceeds in accordance with the Woodward-Hoffmann-DePuy rule. The solvolysis of exo-bicyclo[n.1.0]alkyl p-toluene-sulfonates is assumed to proceed via “semi-open” intermediates, which are somewhere between an allyl cation and a cyclopropyl cation.

Ancillary