A reduced model for shock and detonation waves. II. The reactive case

We present a mesoscopic model for reactive shock waves, which extends a previous model proposed in [G. Stoltz, Europhys. Lett. 76 (2006), 849]. A complex molecule (or a group of molecules) is replaced by a single mesoparticle, evolving according to some Dissipative Particle Dynamics. Chemical reactions can be handled in a mean way by considering an additional variable per particle describing a rate of reaction. The evolution of this rate is governed by the kinetics of a reversible exothermic reaction. Numerical results give profiles in qualitative agreement with all-atom studies

Mechanistic analysis of an asymmetric palladium-catalyzed conjugate addition of arylboronic acids to β-substituted cyclic enones.

An asymmetric palladium-catalyzed conjugate addition reaction of arylboronic acids to enone substrates was investigated mechanistically. Desorption electrospray ionization coupled to mass spectrometry was used to identify intermediates of the catalytic cycle and delineate differences in substrate reactivity. Our findings provide evidence for the catalytic cycle proceeding through formation of an arylpalladium(II) cation, subsequent formation of an arylpalladium-enone complex, and, ultimately, formation of the new C-C bond. Reaction monitoring in both positive and negative ion modes revealed that 4-iodophenylboronic acid formed a relatively stable trimeric species under the reaction conditions

Palladium-Catalyzed Enantioselective C_(sp)^3–C_(sp)^3 Cross-Coupling for the Synthesis of (Poly)fluorinated Chiral Building Blocks

A general method for the enantioselective synthesis of carbo- and heterocyclic carbonyl compounds bearing fluorinated α-tetrasubstituted stereocenters using palladium-catalyzed decarboxylative allylic alkylation is described. The stereoselective C_(sp)^3–C_(sp)^3 cross-coupling reaction delivers five- and six-membered ketone and lactam products bearing (poly)fluorinated tetrasubstituted chiral centers in high yields and enantioselectivities. These fluorinated, stereochemically rich building blocks hold potential value in medicinal chemistry and are prepared using an orthogonal and enantioselective approach into such chiral moieties compared to traditional approaches, often without the use of electrophilic fluorinating reagents

Synthetic Applications and Methodological Developments of Donor-Acceptor Cyclopropanes and Related Compounds

Donor-acceptor cyclopropanes are convenient precursors to reactive and versatile 1,3-dipoles, and have found application in the synthesis of a variety of carbo- and heterocyclic scaffolds. This perspective review details our laboratory’s use of donor-acceptor cyclopropanes as intermediates toward the total synthesis of various natural products. We also discuss our work in the development of novel cycloadditions and rearrangements of donor-acceptor cyclopropanes and aziridines, as well as an example of an aryne insertion proceeding via fragmentation of a transient donor-acceptor cyclobutane

The Open Source Revolution: Transforming the Software Industry with Help from the Government

A new method for making software is stealthily gaining ground in the computer industry, offering a promise of better, cheaper software and the empowerment of the user. The open source movement could revolutionize the software industry...if it succeeds. Open source means software that you are allowed to copy, modify, and give to friends. Source code , the lists of instructions which tell computers how to run, is readily available, allowing you to look inside the workings of a program and change it to suit your needs. A group of programmers, companies, users, and activists have gathered in support of this empowering technology, seeking to persuade businesses and users that open source is the way to go. However, open source faces stiff challenges. The economic basis for the software industry is to charge users by the copy when they buy software. Copying and modification are illegal. The industry and its customers are so mired in this worldview that the idea of giving out a program\u27s recipe, along with a license to change or copy it at will, seems preposterous. Powerful players in the software industry, such as Microsoft, see open source as a threat to their bottom line, and have devoted their energies to discrediting and marginalizing the movement. Beginning from the assumption that cheap, reliable software that empowers the user is a good thing, this thesis looks at the claims made by advocates about the benefits of open source. I explore how the advocates make their case to the business world, the public, and government. I also look at ways in which the government could help bring about an open source revolution, using the policy tools of procurement, research funding, standards enforcement, and antitrust law. I conclude that programmers and public interest lobbyists must join forces to carry this revolution forward, and that the time for action is now, while Microsoft is on trial