The first asymmetric synthesis of (-)-7-epicylindrospermopsin via intramolecular nitrone cycloaddition is described. The synthesis utilized a convergent approach to prepare the cycloaddition precursor 176, which was assembled by condensation of hydroxylamine 175 with aldehyde 145. Hydroxylamine 175 was synthesized from ethylene glycol (166) in seven steps. Aldehyde 145 was completed...
Azaspiracid has generated an enormous amount of scientific interest in the fourteen years since its initial discovery. The structure contains a 6,5,6 bis-spiroketal, a [3.3.1] bicyclic ketal and a 6,5-spiroaminal linkage as key moieties. With 9 rings, 20 stereocenters and three alkenes, the azaspiracid immediately attracted the interest of the...
Azaspiracid-1, a novel marine toxin that contains 9 rings and 20 stereogenic centers, has drawn considerable attention from synthetic groups worldwide due to its structural complexity, which includes a unique trioxabisspiroketal fused to a tetrahydrofuran ring (ABCD rings), a piperidine-tetrahydrofuran spiroaminal system fused to a 2,9-dioxabicyclo[3.3.1]nonane system (FGHI rings), a...
Limnology is undergoing a transition to high-throughput -omic analysis of freshwater
bacterial communities. An important first step in making the transition is to
characterize several genomes that can be used as references to guide metagenome
assembly and analysis. Here I characterize four new freshwater cyanobacterial
genomes, a pair of lake...