Unusual radical cyclisations

Research output: Chapter in Book/Report/Conference proceedingChapter

39 Citations (Scopus)

Abstract

Methods for solving the problems associated with reverse ring opening of small-ring intermediates are described. For three- and four-membered rings particular patterns of substituents are required. Rapid methods of trapping small cyclic structures and extracting them from unfavourable equilibria depend on special new reagents. The new methods enable mono- and polycyclic cyclopropanes and cyclobutanes containing a range of functionality to be readily prepared. Furthermore, several of the newer reagents allow a good measure of stereocontrol to be exercised. Molecules containing the azetidinone ring system (beta-lactam) have been made by no less than four different radical-based disconnections. Syntheses of medium-sized rings invoke endo-type cyclisations and are favoured by precursors containing electron-withdrawing groups at the terminus of the radical acceptor group. Promising routes to seven- and eight-membered lactams are described as well as to 11- and 12-membered lactams. Alternative radical-based strategies for making rings by intramolecular cyclo-dimerisations of diradicals and by intramolecular cyclo-coupling of radicals with carbanionic centres are included.

Original languageEnglish
Title of host publicationRadicals in Synthesis II
EditorsAndreas Gansäuer
PublisherSpringer
Pages163-200
ISBN (Print)978-3-540-31325-0
DOIs
Publication statusPublished - 2006

Publication series

NameTopics in Current Chemistry
Volume264
ISSN (Print)0340-1022
ISSN (Electronic)1436-5049

Keywords

  • synthetic methods
  • radical cyclisations
  • cyclopropanes
  • lactams
  • S-RN(1) reactions
  • KETYL-OLEFIN CYCLIZATION
  • OXIME OXALATE AMIDES
  • ALPHA-BROMO AMIDES
  • MEDIUM-SIZED RINGS
  • BETA-LACTAMS
  • SAMARIUM(II) IODIDE
  • CARBAMOYL RADICALS
  • GAMMA-LACTAMS
  • FUNCTIONALIZED CYCLOBUTANOLS
  • ELECTRON-TRANSFER

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