An approach to 2,4-substituted pyrazolo[1,5-a]pyridines and pyrazolo[1,5-a]azepines by ring-closing metathesis

Article abstract of DOI:10.1002/ejoc.201300901

The ring-closing metathesis (RCM) reactions of dienylpyrazoles have been employed in the synthesis of pyrazolo[1,5-a]pyridine and pyrazolo[1,5-a]azepine derivatives. Based on this approach, the diastereoselective synthesis of potential peptidomimetics containing four amino acid residues with the second (i+1) and third (i+2) fragments having been substituted by bicyclic frameworks is described. The N-allylation of readily available 3,5-substituted pyrazoles followed by ring-closing metathesis of the resulting 1,5-diolefinic derivatives leads to the formation of 2,4-substituted pyrazolo[1,5-a]pyridines and pyrazolo[1,5-a]azepines in high yields. The application of this protocol to the diastereoselective synthesis of potential peptidomimetics is described. Copyright