The imposing andesite stratovolcano is the characteristic expression of subduction zone magmatism, posing hazards to coastal populations and bearing insight into deep Earth processes. On a map of a typical volcanic arc, one can easily distinguish the approximately linear alignment and regular spacing of these major edifices that stand out...
E. coli thioredoxin (TRX) was modified by the episulfonium ion derived from S-(2-chloroethyl)glutathione (CEG) or S-(2-chloroethyl)cysteine (CEC). The alkylation site was located at Cys-32, which was confirmed by tandem mass spectrometry. Two forms of native TRX, Oxi- and Red-TRX, and two modified TRXs, GS- and Cys-TRX, were examined by hydrogen/deuterium...
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...
Aromatic heterocycles are core structural motifs in natural products, pharmaceuticals and biological polymers. Indoles, in particular, represent a significant subclass of aromatic heterocycles, both in terms of sheer numbers, but also in biological and pharmaceutical relevance. As such, new methodologies for the synthesis of indoles represent an important and continually...
The work described herein details the synthesis and application of
biphenyls that probe the effects of hydrogen, Cl / Br, and methyl substituents
on the aryl ring of the terminal acetylenic carbon. From this work, we
successfully developed the rapid synthesis of phenyl acetylenes in 3-4 steps
from inexpensive commercially...
Enantioenriched sp³-hybridized carbenoid reagents CR1R2MX (X = nucleofuge, M = electrofuge) of different types were investigated for the synthesis of polysubstituted alkyl chains by iterative stereospecific reagent-controlled homologation (StReCH) and for the stereospecific connective synthesis of alkenes by eliminative cross-coupling.
In the first part, putative enantioenriched α-chloroalkyllithiums (CHRLiCl) were employed...
Pactamycin, produced by the soil bacterium Streptomyces pactum, is a cytotoxic antibiotic that belongs to the aminocyclitol family of natural products. This antibiotic has shown various forms of biological activity, including antibacterial, antifungal, antimalarial, and antitumor activities. Despite its outstanding biological activity, the mode of formation of its pharmacophore (the...
This work set out to examine the methodologies of dry hopping, compare different hop materials, and look at the extraction behavior of different types of hop compounds. This work consists of two discrete studies, where the first study informed the design of the second.
The first study measured the concentrations...
Two approaches to the tricyclic core of the furanoeremophilane sesquiterpenoids are described. The first approach entails a projected Diels-Alder/retro Diels-Alder reaction of an acetylenic oxazole 64. Construction of the pivotal aldehyde 67 commenced from ketone 68. The acetyenic moiety was then introduced via a Felkin-Ahn addition of lithiopropyne to aldehyde...
Many D2d-symmetric 2,2',6,6'-tetrasubstituted biphenyls are
readily prepared via net oxidative dimerization of appropriate
1,3-disubstituted benzenes. Conversion of such proprochiral
compounds to useful C2-symmetric chiral biphenyls requires
formal replacement of two substituents on opposing aryl ring
units with alternate groups. This under exploited
desymmetrization tactic has been demonstrated for the
generation...