Alexander Ernst

Selective ring N-protection of aminopyrazoles

Abstract Two simple procedures for the selective protection of the ring N of aminopyrazoles as tert -butoxycarbamate (Boc) in high yields are reported; several other protecting groups (Cbz, Bn, SEM) can be introduced using the one-pot procedure (method B). The N -Boc protected aminopyrazoles are acylated at the exocyclic NH 2 group and subsequently deprotected to give the corresponding 3-acylaminopyrazoles in high yields. This procedure is applicable for the rapid parallel synthesis of 3-acylaminopyrazoles.

Synthesis of novel bicyclic ketals of galacturonic acid as potential glycosidase inhibitors

A synthesis of novel bicyclic ketals of galacturonic acid is described. The key cyclisation step was realised under acidic anhydrous conditions in very good yield. X-ray crystal structure analysis determined the correct regio- and stereochemistry.