Recent Advances in the Synthesis of Naturally Occurring Polyhydroxylated Alkaloids

A major fraction of the organic compounds isolated from nature are comprised of nitrogen, oxygen, or sulfur heterocycles. Nirogen-containing substances called alkaloids among them represent a majority of the important medicinal agents discovered in nature. The development of new synthetic methodology for the preparation of such alkaloids and the application of these methods to the synthesis of alkaloidal natural products continue to be an active and exciting area of research in organic chemistry. Especially, polyhydroxylated alkaloids possessing an azetidine-, pyrrolidine-, piperidine-, pyrrolizidine-, or indolizidine-ring structure have attracted a great deal of interest because of their applications from both a biological and a synthetic point of view. Since several reviews have already appeared concerning isolation, structural determination, total synthesis and biological aspects of these compounds independently, the scope of this review is to underline the most recent advances on the synthesis of monohydroxylated, dihydroxylated, and tri- or above hydroxylated bioligically active natural alkaloids containing the ring sturctures described above and related compounds according to those strategies involving prior construction of chiral pools (such as carbohydrates, amino acids, or tartaric acid)-derived crucial lactam intermediates suitable for further chemical elaboration.