Aldonolactones as Chiral Synthons: Preparation of Highly Functionalized, Optically Active Pyrrolidines, Piperidines, Carbocycles and Tetrahydrofurans

This article focusses on the synthetic potential of selectively activated aldonolactones. These are obtained without using any protection group strategy, thus avoiding one of the less attractive features usually associated with polyhydroxylated compounds. The selectively brominated, as well as the sulfonylated, lactones are suitable starting materials for the preparation of hydroxylated and amino substituted pyrrolidines and piperidines, obtained by simple treatment with ammonia. Boiling in water transformed the activated lactones into hydroxylated tetrahydrofurans. Radical-initiated internal ring closure of brominated aldonolactones with unsaturation yields functionalized cyclopentanes regio- and stereospecifically. This results in the synthesis of optically pure carbasugars. Easy manipulation of the hydroxy groups in the cyclopentane-lactones obtained, gives access to other hydroxy/amino substituted cyclopentanes.The type of compounds synthesized are structures of biocogical importance, and the use of aldonolactones as optically active synthons yields optically pure products.