Copper-mediated Chan-Evans-Lam N-arylation of 5-methylene-4-aryl-1,5-dihydro-2H-pyrrol-2-one derivatives

A simple and efficient procedure for the synthesis of N-aryl 5-methylene-4-aryl-1,5-dihydro-2H-pyrrol-2-one derivatives has been developed through copper-mediated CN bond formation. The synthetic protocol allows for versatile and robust CN arylation with a range of readily available boronic acids under mild conditions.     

Quantum design of ionic liquids for extreme chemical inertness and a new theory of the glass transition

In many modern technologies (such as batteries and supercapacitors), there is a strong need for redox-stable ionic liquids. Experimentally, the stability of ionic liquids can be quantified by the voltage range over which electron tunneling does not occur, but so far, quantum theory has not been applied systematically to this problem. Here, we report the electrochemical reduction of a series of quaternary ammonium cations in the presence of bis(trifluoromethylsulfonyl)imide (TFSI) anions and use nonadiabatic electron transfer theory to explicate the results. We find that increasing the chain length of the alkyl groups confers improved chemical inertness at all accessible temperatures. Simultaneously, decreasing the symmetry of the quaternary ammonium cations lowers the melting points of the corresponding ionic liquids, in two cases yielding highly inert solvents at room temperature. These are called hexyltriethylammonium TFSI (HTE-TFSI) and butyltrimethylammonium TFSI (BTM-TFSI). Indeed, the latter are two of the most redox-stable solvents in the history of electrochemistry. To gain insight into their properties, very high precision electrical conductivity measurements have been carried out in the range +20 °C to +190 °C. In both cases, the data conform to the Vogel-Tammann-Fulcher (VTF) equation with “six nines” precision (R ²?>?0.999999). The critical temperature for the onset of conductivity coincides with the glass transition temperature T _g. This is compelling evidence that ionic liquids are, in fact, softened glasses. Finally, by focusing on the previously unsuspected connection between the molecular degrees of freedom of ionic liquids and their bulk conductivities, we are able to propose a new theory of the glass transition. This should have utility far beyond ionic liquids, in areas as diverse as glassy metals and polymer science.     

Some t-Homogeneous Sets of Permutations

Perpendicular Arrays are orderedcombinatorial structures, which recently have found applicationsin cryptography. A fundamental construction uses as ingredientscombinatorial designs and uniformly t-homogeneoussets of permutations. We study the latter type of objects. Thesemay also be viewed as generalizations of t-homogeneousgroups of permutations. Several construction techniques are given.Here we concentrate on the optimal case, where the number ofpermutations attains the lower bound. We obtain several new optimalsuch sets of permutations. Each example allows the constructionof infinite families of perpendicular arrays.     

PHOTOCONTROL OF HYPOCOTYL ELONGATION IN DE-ETIOLATED Cucumis sativus L. A BLUE-LIGHT-INDUCED POST-ILLUMINATION BURST OF GROWTH

Abstract— A rapid transient increase in the growth rate of Cucumis sativus L. seedlings is found to occur after a transition from fluorescent white light to darkness. The post-illumination burst of growth starts after about 20 min of darkness and lasts for 30 to 50 min. The response occurs after long periods of continuous white light, in cycles of white light and darkness, whether the cotyledons are covered or exposed. The post-illumination burst is an expression of the loss of photocontrol of hypocotyl inhibition via the specific blue light photoreceptor because (a) its kinetics resemble those of recovery from blue-light inhibition, and (b) it only occurs on transition from a blue-rich to a blue-poor light environment.     

A Rapid,Nearly Quantitative Conversion of Codeine to Hydrocodone

A very rapid, two-step, virtually quantitative synthesis of hydrocodone from codeine, via the intermediacy of dihydrocodeine, has been developed.     

A Novel Synthesis of Mono- and (1-Ctcloakenyl) Acetic Acid Derivatives via Ionization/Elimination of β-Lactones

Spiro β-lactones undergo an ionization/elimination reaction to afford cycloalkenyl acetic acid derivatives in high yield and isomeric purity.     

A Short Synthesis of γ-Lactams Via the Spontaneous Ring Expansion of β-Lactams

β-Lactams, derived via the cycloaddition of chlorosulfonyl isocyanate to alkenes, undergo thermal rearrangement at room temperature to afford γ-lactams.