The Aryne-Abramov Reaction as a 1,2-Benzdiyne Platform for the Generation and Solvent-Dependent Trapping of 3-Phosphonyl Benzynes.

Synthetic methodology utilizing two aryne intermediates (i.e., a formal benzdiyne) enables the rapid generation of structurally complex molecules with diverse functionality. This report describes the sequential generation of two ortho-benzyne intermediates for the synthesis of 2,3-disubstituted aryl phosphonates. Aryl phosphonates have proven useful in medicinal chemistry and materials science, and the reported methodology provides a two-step route to functionally dense variants by way of 3-phosphonyl benzyne intermediates. The process begins with regioselective trapping of a 3-trifloxybenzyne intermediate by an O-silyl phosphite in an Abramov-like reaction to bond the strained Csp carbons with phosphorus and silicon. Standard aryne-generating conditions follow to convert the resulting 2-silylphenyl triflate into a 3-phosphonyl benzyne, which readily reacts with numerous aryne trapping reactants to form a variety of 2,3-difunctionalized aryl phosphonate products. DFT computational studies shed light on important mechanistic details and revealed that 3-phosphonyl benzynes are highly polarizable. Specifically, the distortion in the internal bond angles at each of the Csp atoms was strongly influenced by both the electronegativity of the phosphonate ester groups as well as the dielectric of the computational solvation model. These effects were verified experimentally as the regioselectivity of benzyl azide trapping increased with more electronegative esters and/or increasingly polar solvents. Conversely, replacing the conventional solvent, acetonitrile, with nonpolar alternatives provided attenuated or even inverted selectivities. Overall, these studies showcase new reactivity of benzyne intermediates and extend the aryne relay methodology to include organophosphonates. Furthermore, this work demonstrates that the regioselectivity of aryne trapping reactions could be tuned by simply changing the solvent.

Rhodium-Catalyzed Enantioselective Intramolecular Hydroacylation of Trisubstituted Alkenes.

We report the first examples of transition metal-catalyzed enantioselective alkene hydroacylations with 1,1,2-trisubstituted alkenes. DFT and mechanistic studies are consistent with a reaction pathway for these rhodium-catalyzed processes including intramolecular alkene hydroacylation and α-epimerization to generate highly enantioenriched, polycyclic architectures. This reaction sequence enables the hydroacylation of 2-(cyclohex-1-en-1-yl)benzaldehydes to form hexahydro-9H-fluoren-9-ones in moderate to high yields (68-91 %) with high enantioselectivities (up to 99 % ee) and diastereoselectivities (typically >20:1).

On the directionality of halogen bonding.

The origin of the high directionality of halogen bonding was investigated quantum chemically by a detailed comparison of typical adducts in two different orientations: linear (most stable) and perpendicular. Energy decomposition analyses revealed that the synergy between charge-transfer interactions and Pauli repulsion are the driving forces for the directionality, while electrostatic contributions are more favourable in the less-stable, perpendicular orientation.

Dealing with mass death in disasters and pandemics: Some key differences but many similarities.

PURPOSE: There are many differences in how authorities handle the dead during mass death incidents involving disasters and pandemics. These differences would suggest that planning for a disaster death and planning for a pandemic death should be done separately. This may be true to some extent, however, there are many similarities between the two that this article will seeks to examine. The main objective of this study is to show that planning for both disasters and pandemics should either be done by a single entity that coordinates both types of responses, or by agencies that communicate closely and frequently. DESIGN/METHODOLOGY/APPROACH: This study compared mass death incidents predominantly within the Canadian historical record, including disasters and pandemics. It took a specific look at the influenza pandemic of 1918 in North America and how the dead were handled. FINDINGS: Both disasters and pandemics offer unique challenges in handling the dead and documenting the incident. In a pandemic the cause of death is usually clear, while in a disaster it is not always understood. However, the similarities they hold in common must not be overlooked. They will involve immense and complicated amounts of paperwork, cause a shortage of supplies (be it medical, food or otherwise) and create the need for assistance. ORIGINALITY/VALUE: The research finds that though disasters and pandemics are often handled differently by the various agencies involved, they should be treated alike and dealt with in the same manner.

Chemically contaminated casualties: different problems and possible solutions.

The initial response to mass casualty incidents is usually informal as uninjured and injured survivors and passersby assist the injured and take them to medical centers. This creates some problems, for example, most victims go to one or two hospitals and the least injured arrive first; but, on the whole, it works. However, the same response does not work when victims are contaminated, and some of the solutions that work when victims are only injured do not work when victims are contaminated. This article suggests an approach that accepts the reality of what happens-the first receiving hospital becomes contaminated--and suggests how planning can begin with that as a starting point. It stressed that current plans are based on false assumptions and that this can lead to inadequate preparation.

Almost only women: Canadian volunteer response to the 1918-1920 pandemic.

When pandemic influenza arrived from the United States in 1918-1920 to strike Canada with devastating force, the health system was overwhelmed. Although emergency hospitals were established in public buildings including schools and universities, many sick remained in their homes. Because of the war, many physicians and nurses were overseas. Many of those who were in Canada became flu victims. The result was a massive call for volunteers. Although a few men responded, most volunteers were women. These women, many of whom had little or no training, risked their lives by acting as nurses in existing and emergency hospitals and by assisting sick families in their homes. Many became ill and some died. The result is an incredible portrait of volunteer response to a major medical emergency.

Reactions of copper(II)-H2O2 adducts supported by tridentate bis(2-pyridylmethyl)amine ligands: sensitivity to solvent and variations in ligand substitution.

The copper(II) complexes 1(H) and 1(Ar(X)), supported by the N,N-di(2-pyridylmethyl)benzylamine tridentate ligand (L(H)) or its derivatives having m-substituted phenyl group at the 6-position of pyridine donor groups (L(Ar(X))), have been prepared, and their reactivity toward H2O2 has been examined in detail at low temperature. Both copper(II) complexes exhibited a novel reactivity in acetone, giving 2-hydroxy-2-hydroperoxypropane (HHPP) adducts 2(H) and 2(Ar(X)), respectively. From 2(Ar(X)), an efficient aromatic ligand hydroxylation took place to give phenolate-copper(II) complexes 4(Ar(X)). Detailed spectroscopic and kinetic analyses have revealed that the reaction proceeds via an electrophilic aromatic substitution mechanism involving copper(II)-carbocation intermediates 3(Ar(X)). Theoretical studies at the density functional theory (DFT) level have strongly implicated conjugate acid/base catalysis in the O-O bond cleavage and C-O bond formation steps that take the peroxo intermediate 2(Ar(X)) to the carbocation intermediate 3(Ar(X)). In contrast to the 2(Ar(X)) cases, the HHPP-adduct 2(H) reacted to give a copper(II)-acetate complex [Cu(II)(L(H))(OAc)](ClO4) (6(H)), in which one of the oxygen atoms of the acetate co-ligand originated from H2O2. In this case, a mechanism involving a Baeyer-Villiger type 1,2-methyl shift from the HHPP-adduct and subsequent ester hydrolysis has been proposed on the basis of DFT calculations; conjugate acid/base catalysis is implicated in the 1,2-methyl shift process as well. In propionitrile, both 1(H) and 1(Ar(X)) afforded simple copper(II)-hydroperoxo complexes LCu(II)-OOH in the reaction with H2O2, demonstrating the significant solvent effect on the reaction between copper(II) complexes and H2O2.

Characterization of Co-C bonding in dichlorovinylcobaloxime complexes.

This study combines theory and experiment in an examination of Co-C bonding and reductive Co-C cleavage in cobalt dichlorovinyl complexes. It is motivated by the role of dichlorovinyl complexes as intermediates in the dechlorination of trichloroethylene by cobalamin and cobalamin model complexes. A series of seven cis-1,2-dichlorovinyl(L)cobaloxime complexes were prepared (L = m- and p-substituted pyridines; cobaloxime = bis(dimethylglyoximato)cobalt). The complexes were characterized using 1H NMR, 13C NMR, cyclic voltammetry, and X-ray crystallography. Examination of the metrical parameters of the Co-C=C unit across the series shows very little change in the C=C bond length and a slight increase in the Co-C bond length with increasing electron-donating ability of the pyridine ligand. These structural changes along with electronic structure calculations indicate that Co-C pi-bonding is not important in these complexes. The stronger Co-C bonds of vinylcobaloximes compared to those of alkylcobaloximes are best explained by the higher s character at C. Changes in the reduction potential across the series indicate that the pyridine-bound form is the primary electrochemically active species. Theoretical examination of the Co-C cleavage following reduction supports the direct formation of the cis-1,2-dichlorovinyl anion and not the cis-1,2-dichlorovinyl radical.

Sampling an unknown universe: problems of researching mass casualty incidents (a history of ECRU's field research).

This paper reviews how the Emergency Communications Research Unit (ECRU) at Carleton University in Ottawa, Canada, developed its field research techniques with emphasis on some of its approaches to sampling. Then based on ECRU's experience, it discusses the problems that would arise if an attempt were made to research an incident involving not only mass casualties, but also chemically contaminated mass casualties. While ECRU's findings have been published in scores of book chapters, monographs and academic and other articles, this is only the second time since 1977 that its methods have been described [The Development of a Standby Research Capacity at Carleton University. Emergency Planning: Ottawa, Canada; Int. J. Mass Emergencies and Disasters 1977; 2(1):35-41; Methods of Disaster Research. Xlibris Corporation, 26-302], and the very first time its approaches to sampling have been discussed.

Not just bigger but different : The problems of planning for disaster

A detailed analysis of the police response to disasters (Hagersville tire fire, Edmonton tornado) shows that a disaster is not merely a large scale emergency; it has characteristics of its own. In disaster police can be called upon to make decisions not encountered inthe normal line of duty. Good planning to work in coordination with other agencies