A convergent synthesis of epothilone B that generates all seven of its
asymmetric centers in a completely stereoselective fashion has been
completed. Key reactions include an anti-Felkin aldol condensation to
set the C6 and C7 stereochemistry, a directed α-hydroxylation to install
the C15 (S)-hydroxyl substituent, and a Wittig condensation to...
This thesis is an account of my explorations into the field of natural products chemistry. These investigations led to the discovery of several novel secondary metabolites isolated from the marine cyanobacterium Lyngbya majuscula. In addition, biosynthetic investigations were undertaken using stable isotope-labeled precursors. The dominant role that NMR spectroscopy plays...
Myxobacteria represent an interesting class of Gram-negative soil bacteria. These bacteria utilize organic materials from the environment as a food source by the action of their extracellular hydrolytic enzymes. They grow vegetatively in the presence of adequate nutrients. During starvation conditions, however, they aggregate and form multicellular structures called fruiting...
The discovery of new antibiotics reached its peak during the golden era of antibiotics in the mid 20th century and continued to thrive until the 1980s. However, after more than 50 years of fruitful exploration and exploitation of microbial natural products the discovery rate of new antibiotics has dropped drastically...
This thesis describes the chemical investigation of marine cyanobacteria collected in Madagascar and Panama with an emphasis on the isolation and structure elucidation of medicinally relevant secondary metabolites.
A collection of the marine cyanobacterium Lyngbya majuscula from the Radames Islands, Madagascar yielded two new cyclic depsipeptides, radamamides A and B,...
A gene cluster responsible for the biosynthesis of the antitumor agent
cetoniacytone A was identified in Actinomyces sp. strain Lu 9419, an
endosymbiotic bacteria isolated from the intestines of the rose chafer beetle. The
nucleotide sequence analysis of the 26 Kb DNA region revealed the presence of 17
complete ORFs,...
Among the myriad of naturally occurring bioactive compounds are the aminocyclopentitol-containing natural products that represent a family of sugar-derived microbial secondary metabolites, such as the antibiotics pactamycin, allosamidin, and trehazolin. Pactamycin, a structurally unique aminocyclitol antibiotic isolated from Streptomyces pactum, consists of a 5-membered ring aminocyclitol (cyclopentitol) unit, two aromatic...