Novel Pyrrolo[2,3-d]pyrimidine Ring forming Methodology

A short, succinct route to biologically active and medicinally important pyrrolo[2,3-d]pyrimidines has been developed starting from readily available acyclic aldehydes. A very efficienttwo step sequence involving a Knoevenagel condensation followed by copper mediated 1,4-conjugate of vinyl magnesium bromide sets up the acyclic precursor. Then, guanidine cyclization followed by a palliduim catalyzed amination reaction or ozonolytic cleavage of the vinyl substituent followed by guanidine cyclization and intramolecular imine formation complete the synthesis.     

Collaborative statistical investigations in diverse settings

This study presents a continuing investigation of influences on outcomes achieved by students working in groups of three on tasks related to chance and data. Earlier research described final mathematical outcomes and identified 17 factors influencing three types of short-term outcomes for groups working in an isolated setting. The current report documents the 17 factors for groups working in a classroom setting and 1654 events for all groups in both settings are identified and each associated with a factor and a short-term outcome. Consideration is then given to variables that have the potential to influence the factors, the short-term outcomes, and their interaction. The overarching variable is the setting within which the collaboration took place. Within each setting, however, two other variables operated: the task carried out, the age/grade of students, gender balance, or collaborative characteristics. The influences of these variables are described within the two settings before consideration is given to the overall influence of the settings.     

C-D(0) (D(0) = pi-donor, F) Cleavage in H(2)C=CH(D(0)) by (Cp(2)ZrHCl)(n): mechanism, agostic fluorines, and a carbene of Zr(IV).

Consistent with the C-O cleavage behavior of vinyl ethers, vinyl fluoride reacts with Cp(2)ZrHCl to give Cp(2)ZrFCl and C(2)H(4) as primary products. DFT (B3PW91) calculations show this reaction to be highly exoenergetic (-55 kcal/mol), and reveal a sigma-bond metathesis mechanism to be unfavorable compared to a Zr-H addition across the C=C bond, with regiochemistry placing F on C(beta) of the resulting fluoroethyl ligand. beta-F elimination (onto Zr) then completes the reaction. There is no eta(2)-olefin intermediate on the reaction path. DFT calculations seeking the energy and structure of the two carbenes Cp(2)ZrHCl[CF(CH(3))] and Cp(2)ZrFCl[CH(CH(3))] are also described.     

Underwater visual inspection and measurement using optical holography

In offshore oil and gas exploration, visual inspection and measurement often has to be carried out under conditions of poor visibility and at great depths. Recording a hologram of an underwater scene with its subsequent replay in the laboratory could provide enormous benefits to the inspection engineer. When replayed in the real image mode, dimensional measurement may be performed directly on the image formed in real space using, for example, measuring microscopy or TV cameras. Potential applications include general archiving, measurement of corrosion pitting and cracking, examination and measurement of damage sites, structural profiling and examination of marine growth. In this paper, we outline the general concepts of underwater holography. A résumé is given of the work undertaken in the past, the problems experienced and their solution and an indication of our general direction leading to the establishment of holography as a unique method of subsea inspection.     

OPPORTUNITY COSTS OF FEDERAL LAND-USE RESTRICTIONS FOR U.S. COAL MARKETS

U.S. federal government land-use restrictions limit access to high-quality, low-cost coal on federal lands in the western U.S. The main purpose of these limits is to protect the environment. A substantial amount of U.S. coal resources has been set aside, about 67 billion tons, which represents 27% of total U.S. surface-minable coal. Debate has focused on the environmental benefits attained by the land-use restrictions; little effort has gone into the explicit quantification of opportunity costs. To help fill that gap, this analysis examines the long-term effects that these restrictions could have on the national cost of meeting future coal demands, including impacts on regional patterns of coal availability and production.