A Suzuki coupling based route to 2,2'-bis(2-indenyl)biphenyl derivatives.

Because of the promising performance in olefin polymerization of 2,2'-bis(2-indenyldiyl)biphenyl zirconium dichloride, we developed a new and broadly applicable route to 2,2'-bis(2-indenyl)biphenyl derivatives. Reaction of the known 2,2'-diiodobiphenyl (26) with the new 2-indenyl boronic acid (23) did not result in the desired 2,2'-bis(2-indenyl)biphenyl (10); instead an isomer thereof, (spiro-1,1-(2,2'-biphenyl)-2-(2-indenyl)indane) (27), was obtained. It was found that compound 10 could be made via a palladium-catalyzed reaction of 2,2-biphenyldiboronic acid (31) with 2-bromoindene (21) under standard Suzuki reaction conditions. However, the yield of this reaction was low at low palladium catalyst loadings, due to a competitive hydrolysis reaction of 2,2-biphenyldiboronic acid (31). HTE techniques were used to find an economically viable protocol. Thus, use of the commercially available 1.0 molar solution of (n-Bu)(4)NOH in methanol with cosolvent toluene led to precipitation of the pure product in a fast and clean reaction, using only 0.7 mol % (0.35 mol % per C-C) of the expensive palladium catalyst.     

Synthesis and antimalarial activity of a series of 2,4-diamino-6-[(N-alkylanilino)methyl]quinazolines

A series of 2,4-diamino-6-[(N-alkylanilino)methyl]quinazolines were prepared by bromination of 2,4-dibenz-amido-6-methylquinazoline followed by treatment with secondary arylamines and deblocking with base. A variety of analogs demonstrated substantial activity against Plasmodium berghei infections in mice.     

Non-planar axial Me2N in cis-2-dimethylamino-2-thio-5-t-butyl-1,3,2-oxazaphosphorinane

An X-ray crystallographic study of the title compound shows it to have an axial Me₂N with pyramidal N and a lengthened N-P bond. Conversely, the endocyclic NH-P bond is shortened. The origins of these effects are assigned to specific geometrical relationships of the Me₂N/P=S and NH/P=S groupings imposed by the ring system.     

Wetting and wetting transitions on copper-based super-hydrophobic surfaces

Rough and patterned copper surfaces were produced using etching and, separately, using electrodeposition. In both of these approaches the roughness can be varied in a controlled manner and, when hydrophobized, these surfaces show contact angles that increase with increasing roughness to above 160 degrees . We show transitions from a Wenzel mode, whereby the liquid follows the contours of the copper surface, to a Cassie-Baxter mode, whereby the liquid bridges between features on the surface. Measured contact angles on etched samples could be modeled quantitatively to within a few degrees by the Wenzel and Cassie-Baxter equations. The contact angle hysteresis on these surfaces initially increased and then decreased as the contact angle increased. The maximum occurred at a surface area where the equilibrium contact angle would suggest that a substantial proportion of the surface area was bridged.     

Optimal ternary linear codes

Let n _q (k, d) denote the smallest value of n for which there exists a linear [n, k, d]-code over GF(q). An [n, k, d]-code whose length is equal to n _q (k, d) is called optimal. The problem of finding n _q (k, d)has received much attention for the case q = 2. We generalize several results to the case of an arbitrary prime power q as well as introducing new results and a detailed methodology to enable the problem to be tackled over any finite field.In particular, we study the problem with q = 3 and determine n ₃(k, d) for all d when k 4, and n ₃(5, d) for all but 30 values of d.     

Substituent effects on O–H and S–H bond dissociation enthalpies of disubstituted phenols and thiophenols

The O–H and S–H homolytic bond dissociation enthalpies of a set of disubstituted phenols and thiophenols (NH₂, OH, CH₃, Cl, CF₃, and NO₂) have been computed by a density functional theory procedure with the 6‐311++G(d,p) basis set. A very good agreement between our results and available experimental ones is observed. The effect of substituents on structure, charges and BDEs are investigated and their correlation with Hammett parameters is studied. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008