Synthesis of annelated pyranosides: a rapid and efficient entry to highly functionalized optically pure branched-pyrazoles

Pyrazolo-pyranosides prepared from methyl-2,3:4,6-di-O-benzylidene-α-d-mannopyranoside were functionalized to design new scaffolds suitable for peptidomimetic construction. Under certain acidic conditions, they undergo only pyranose ring-opening generating highly functionalized optically pure pyrazoles bearing an aldehyde function.