Total Synthesis of The Bidensyneosides; Remarkable Protecting Group Effects in Glycosylation And Synthetic Efforts Towards The Total Synthesis of A Pentaacetylenic Glucoside
This document describes the work towards the synthesis of polyacetylene glucosides isolated from nature. Theses syntheses represent the first total synthesis of the bidensyneosides (1-5) isolated from Bidens parviflora. Biological assays have shown that the bidensyneosides effectively regulate histamine release and nitric oxide production. Additionally, a remarkable protecting group effect was observed during glycosylations, effectively showing that the nature of the protecting group can lead to a differentiation between the orthoester and anomeric product. Furthermore, an attempt to assemble a pentaacetylenic glucoside 34 isolated from Microglossa pyrifolia was undertaken. The assembly consists of a glycosylation followed by a triply convergent unsymmetrical cross coupling to give a pentaacetylene. To this end, the establishment of conditions capable of producing a pentaacetylene without subsequent addition of base to the electrophilic pentaacetylene side chain has been unsuccessful. Further studies of these conditions should lead to the desired product, which after deprotection would give the natural product.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:natural products acetylenic glucosides polyacetylene glycosylation total synthesis bidensyneosides
Date of Publication:01/01/2004