Platinum(II)-catalyzed intermolecular hydroamination of monosubstituted allenes with secondary alkylamines.

A 1:1 mixture of (dppf)PtCl(2) and AgOTf (5 mol%) catalyzed the intermolecular hydroamination of monosubstituted allenes with secondary alkylamines at 80 degrees C to form allylic amines in good yield with selective formation of the E-diastereomer.

Tyrosine phosphorylation of G protein alpha subunits by pp60c-src.

A number of lines of evidence suggest that cross-talk exists between the cellular signal transduction pathways involving tyrosine phosphorylation catalyzed by members of the pp60c-src kinase family and those mediated by guanine nucleotide regulatory proteins (G proteins). In this study, we explore the possibility that direct interactions between pp60c-src and G proteins may occur with functional consequences. Preparations of pp60c-src isolated by immunoprecipitation phosphorylate on tyrosine residues the purified G-protein alpha subunits (G alpha) of several heterotrimeric G proteins. Phosphorylation is highly dependent on G-protein conformation, and G alpha(GDP) uncomplexed by beta gamma subunits appears to be the preferred substrate. In functional studies, phosphorylation of stimulatory G alpha (G alpha s) modestly increases the rate of binding of guanosine 5'-[gamma-[35S]thio]triphosphate to Gs as well as the receptor-stimulated steady-state rate of GTP hydrolysis by Gs. Heterotrimeric G proteins may represent a previously unappreciated class of potential substrates for pp60c-src.

Development of Stimulus-Responsive Ligands for the Modulation of Copper and Iron Coordination

The ability to manipulate the coordination chemistry of metal ions has significant ramifications for the study and treatment of metal-related health concerns, including iron overload, UV skin damage, and microbial infection among many other conditions. To address this concern, chelating agents that change their metal binding characteristics in response to external stimuli have been synthesized and characterized by several spectroscopic and chromatographic analytical methods. The primary stimuli of interest for this work are light and hydrogen peroxide.

Herein we report the previously unrecognized photochemistry of aroylhydrazone metal chelator ((E)-N′-[1-(2-hydroxyphenyl)ethyliden]isonicotinoylhydrazide) (HAPI) and its relation to HAPI metal binding properties. Based on promising initial results, a series of HAPI analogues was prepared to probe the structure-function relationships of aroylhydrazone photochemistry. These efforts elucidate the tunable nature of several aroylhydrazone photoswitching properties.

Ongoing efforts in this laboratory seek to develop compounds called prochelators that exhibit a switch from low to high metal binding affinity upon activation by a stimulus of interest. In this context, we present new strategies to install multiple desired functions into a single structure. The prochelator 2-((E)-1-(2-isonicotinoylhydrazono)ethyl)phenyl (E)-3-(2,4-dihydroxyphenyl)acrylate (PC-HAPI) is masked with a photolabile trans-cinnamic acid protecting group that releases umbelliferone, a UV-absorbing, antioxidant coumarin along with a chelating agent upon UV irradiation. In addition to the antioxidant effects of the coumarin, the released chelator (HAPI) inhibits metal-catalyzed production of damaging reactive oxygen species. Finally a peroxide-sensitive prochelator quinolin-8-yl (Z)-3-(4-hydroxy-2-((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)phenyl)acrylate (BCQ) has been prepared using a novel synthetic route for functionalized cis-cinnamate esters. BCQ uses a novel masking strategy to trigger a 90-fold increase in fluorescence emission, along with the release of a desired chelator, in the presence of hydrogen peroxide.

Ambient Noise in the Kitimat Fjord System

Sound is an important medium for communication and marine organisms have evolved to capitalize on the efficiency with which sound energy travels through water. Anthropogenic and natural sound sources contribute to ocean ambient noise, which can interfere with the use of this sensory modality by marine animals. Anthropogenic noise sources have been increasing steadily over recent decades largely due to coastal population growth, increased global transportation, and offshore industrialization. Understanding the potential impacts of anthropogenic noise requires the establishment of ambient acoustic baselines from which to measure change. Establishing baselines, especially in quiet areas still largely unaffected by anthropogenic stressors, is particularly crucial in the face of the expansion of offshore industries, increasing coastal population and growing reliance on the ocean for global transportation. Global demand for liquid natural gas (LNG), catalyzed primarily by a growing Asian market, is expected to increase significantly in the next 20 years. The geographic position of British Columbia relative to these markets, a growing supply of LNG and new technology for extraction and shipping situate British Columbia as a strong competitor in the lucrative market. The LNG industry could have many adverse impacts on these territories and ecosystems. The Kitimat Fjord System is slated for the development of these LNG export facilities increasing shipping traffic for the port and thus increasing ambient noise in the fjord system. The purpose of this study is to 1) quantify the existing sound levels in the area surrounding Gil Island and 2) identify potential source mechanisms in order to provide a baseline study of the acoustic environment in the Kitimat Fjord system prior to potential increases from LNG shipping.