1,3-dipolar cycloadditions of trimethylsilyldiazomethane revisited: steric demand of the dipolarophile and the influence on product distribution

J Org Chem. 2007 Jan 19;72(2):650-3. doi: 10.1021/jo061838t.


The 1,3-dipolar cycloaddition of trimethylsilyldiazomethane with alpha,beta-unsaturated esters was examined. The resulting 1-pyrazolines isomerize to regioisomeric 2-pyrazolines (a or b) or undergo desilylation (c). Acrylates yield only b or c. beta-Substituted dipolarophiles may yield all three types of products. This work demonstrates that the distribution of 2-pyrazoline products is highly dependent on the relative configuration of the substituents on the 1-pyrazoline intermediate.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cyclization
  • Diazomethane / analogs & derivatives*
  • Diazomethane / chemical synthesis
  • Diazomethane / chemistry
  • Esters / chemistry*
  • Molecular Structure
  • Stereoisomerism
  • Trimethylsilyl Compounds / chemical synthesis
  • Trimethylsilyl Compounds / chemistry*


  • Esters
  • Trimethylsilyl Compounds
  • Diazomethane
  • trimethylsilyldiazomethane