Investigation of macrocyclisation routes to 1,4,7-triazacyclononanes: efficient syntheses from 1,2-ditosylamides

Org Biomol Chem. 2008 Jan 21;6(2):374-84. doi: 10.1039/b716938h. Epub 2007 Dec 11.

Abstract

Two routes to the synthesis of a cyclohexyl-fused 1,4,7-triazacyclononane involving macrocyclisations of tosamides have been investigated. In the first approach, using a classic Richman-Atkins-type cyclisation of a cyclohexyl-substituted 1,4,7-tritosamide with ethylene glycol ditosylate, afforded the cyclohexyl-fused 1,4,7-triazacyclononane in 5.86% overall yield in four steps. The second, more concise, approach involving the macrocyclisation of trans-cyclohexane-1,2-ditosamide with the tritosyl derivative of diethanolamine initially gave poor yields (< 25%). The well-documented problems with efficiencies in macrocyclisations using 1,2-ditosamides led to the use of a wider range of 1,2-ditosamides including ethane-1,2-ditosamide and propane-1,2-ditosamide. These extended studies led to the development of an efficient macrocyclisation protocol using lithium hydride. This new method afforded 1,4,7-tritosyl-1,4,7-triazacyclononanes in good yield (57-90%) from 1,2-ditosamides in a single step. These efficient methods were then applied to the preparation of a chiral cyclohexyl-fused 1,4,7-tritosyl-1,4,7-triazacyclononane (65-70%). This key chiral intermediate was then converted into a copper(ii) complex following detosylation and N-methylation. The resulting chiral copper(ii) complex catalysed the aziridination of styrene but it did so in a racemic fashion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides / chemistry*
  • Crystallography, X-Ray
  • Cyclization
  • Heterocyclic Compounds / chemical synthesis*
  • Heterocyclic Compounds / chemistry
  • Models, Molecular
  • Molecular Structure
  • Stereoisomerism
  • Tosyl Compounds / chemistry*

Substances

  • Amides
  • Heterocyclic Compounds
  • Tosyl Compounds
  • 1,4,7-triazacyclononane