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High surface area materials are of considerable interest for gas and analyte storage/capture, molecular sieving, catalyst supports, and slow release delivery systems. This paper set out to gain a fundamental understanding of the influence reaction parameters have on structure–property relationships of fluoride-catalyzed methylsilsesquioxane based porous networks. For this study, twelve solvents of varying polarities were used and were compared for their effect on gelation and final properties related to porosity, hydrophobicity, and solvent uptake. We find that solvent choice and water compatibility plays an extremely important role in gaining specific pore size distributions, surface areas and gel types, with a consistent cross-linker size and length. Reactions conducted in acetonitrile and dichloromethane offer surface areas >1000 m2 g−1, but with acetonitrile being mesopore dominant and having global gel formation versus dichloromethane, which is micropore dominant and gave gel particles. The difference in these reactions comes from their variances in solvation of monomer/oligomer and water. In addition to these findings, swelling studies of gels made from acetonitrile result in >700% by mass solvent reabsorption after drying out. This study enhances the toolbox for continued improvement and development of thermally stable, selective analyte uptake, porous materials.

Heterocycles are very common substructures in a number of pharmaceuticals. Over the past several years, the use of palladium-catalyzed oxidative cyclization for heterocyclic synthesis has become much more prevalent. This review collects recent reports using palladium catalysis to synthesize a wide variety of heterocyclic scaffolds. Many of these reactions use oxygen as the terminal oxidant. Some salient mechanistic features are discussed.

Two linkage isomers composing of diironhexacarbonyl clusters coupled to α and p -toluenethiolate ligands have been usefully prepared in moderate yields. The composition of both compounds, [( μ 2 -( p -toluenethiolato)) 2 Fe 2 (CO) 6 ] ( 1 ) and [( μ 2 -( α -toluenethiolato)) 2 Fe 2 (CO) 6 ] ( 2 ), have been determined by elemental analysis and NMR spectroscopy. A tetrairondodecacarbonyl complex, [ μ 4 -S ( μ 2 -( α -toluenethiolato)Fe 2 (CO) 6 ) 2 ] ( 3 ), was isolated from the reaction mixture of 2 . The molecular structures of 2 and 3 determined by X-ray diffraction are discussed. An exploration of the influence of the α- and p -toluenethiolate ligands on the electronic and electrochemical properties of the iron-carbonyl units have been accomplished using infrared spectroscopy, UV–Vis spectroscopy and cyclic voltammetry. In the presence of acetic acid, compounds 1 , 2 and 3 catalyze the electrochemical generation of molecular hydrogen. The proton reduction overpotentials for compounds 1 and 2 were determined to be 0.76 V and 0.85 V versus Fc/Fc + respectively in acetonitrile as solvent. Comparatively, compound 1 produces hydrogen at an overpotential 90 mV lower than compound 2 .

Oxygenated, polycyclic terpenoid natural products have important biological activities. Although total synthesis of such terpenes is widely studied, synthetic strategies that allow for controlled placement of oxygen atoms and other functionality remains a challenge. Herein, we present a simple, scalable, and tunable synthetic strategy to assemble terpenoid-like polycycloalkanes from cycloalkanones, malononitrile, and allylic electrophiles, abundantly available reagent classes.

The oxidative functionalization of olefins is a common method for the formation of vicinal carbon-heteroatom bonds. However, oxidative methods to transform allenes into synthetic motifs containing three contiguous carbon-heteroatom bonds are much less developed. This paper describes the use of bicyclic methylene aziridines (MAs), prepared via intramolecular allene aziridination, as scaffolds for functionalization of all three allene carbons.

Stable palladapyrrolidinones (L-L)Pd-CH(p-MeC6H4)NBnC(═O)CHPh representing endocyclic carbon-bonded palladium(II) amide enolates with two Pd-bonded sp3-hybridized stereogenic carbons and bidentate ...

A brief history of mechanical gyroscopes and their applications is followed by a summary of properties that are desirable in molecular gyroscopes. Molecules to which the descriptor gyroscope has been applied are then reviewed through early 2002. Syntheses as well as structural and dynamic properties of the macrocyclic platinum complexes trans- ( Cl ) ( C 6 F 5 ) Pt ( PP h 2 ( C H 2 ) 2 n + 2 P ⎴ P h 2 ) (n = 4, 5, 6, 8, 9), in which a single methylene chain spans the trans phosphorus atoms, are subsequently analyzed. No part of the Cl-Pt-C6F5 moiety can rotate through the macrocycle when it consists of 13 atoms; however, the chloride ligand can pass through macrocycles of ≥15 atoms, and the pentafluorophenyl ligand through macrocycles of ≥21 atoms. Analogous complexes in which two methylene chains span the trans phosphorus atoms are also discussed.

[reaction: see text] Oxapalladacycles were immobilized on polystyrene-divinylbenzene supports and treated with 3-aryl-2-propynoates or 1-alkyl-1,2-propadienes to afford 2H-1-benzopyrans in yields superior to those for solution-phase experiments. Isolation of benzopyrans was facilitated, and 71-80% of the palladium was recovered. Effects of resin loading with phosphorus and palladium were studied, and the optimum immobilized palladacycles featuring a medium loading with P (1.35 mmol P/g) and a high loading with Pd (Pd:P ratio 1:1.7) were identified. Resins with higher swelling capacities were more reactive.

The rearrangement of nitrones to lactams can be carried out by photochemical activation or by treatment with Tf(2)O followed by KOH-promoted rearrangement (a modification of conditions originally introduced by Barton). Substrates in which the nitrone is part of a fused bicyclic ring system have traditionally proven problematic for this kind of reaction. In this study, a series of mono-, bi-, and tricyclic ring-fused nitrones were prepared to investigate the dependence of products on nitrone ring size and tether length. Results indicated that photochemical rearrangement of nitrones in benzene afforded reasonably good yields (30-68%) of lactams, while the two-step nonphotochemical process provided slightly better average yields (30-95%) of the same targets.

Nitrogen-containing stereotriads occur in a number of biologically active compounds, but general and flexible methods to access these compounds are limited mainly to the manipulation of chiral olefins. An alternative approach is to employ a highly chemo-, regio-, and stereocontrolled allene oxidation that can install a new carbon–heteroatom bond at each of the three original allene carbons. In this paper, an intramolecular/intermolecular allene bis-aziridination is described that offers the potential to serve as a key step for the construction of stereotriads containing vicinal diaminated motifs. The resultant 1,4-diazaspiro[2.2]pentane (DASP) scaffolds contain two electronically differentiated aziridines that undergo highly regioselective ring-openings at C1 with a variety of heteroatom nucleophiles to give chiral N,N-aminals. Alternatively, the same DASP intermediate can be induced to undergo a double ring opening reaction at both C1 and C3 to yield vicinal diaminated products corresponding to formal ring opening at C3. The chirality of a propargyl alcohol is easily transferred to the DASP with good fidelity, providing a new paradigm for the construction of enantioenriched nitrogen-containing stereotriads.

A variety of allene substrates is transformed to bicyclic methylene aziridines bearing electron-withdrawing groups at the aziridine nitrogen.

Scant data exist regarding patient outcome after treatment of abdominal compartment syndrome (ACS) with decompressive laparotomy. This work reviews the outcome of 25 burn patients at a single institution who underwent decompressive laparotomy for treatment of ACS in the periresuscitation period. A computerized burn registry and directed chart review were used for data collection and analysis in this retrospective review. From September 1996, 25 patients underwent decompressive laparotomy after developing ACS. Mean burn size was 65 +/- 19% TBSA. Mean age was 28 +/- 19 years. Twenty-two (88%) died. Myo/ hemoglobinuria was present at admission in eight patients, one of whom survived. Fourteen patients had inhalation injury, of whom two survived. Before decompressive laparotomy, mean bladder pressure and peak inspiratory pressure were 57 +/- 4.2 mm Hg and 41 +/- 2.2 mm Hg, respectively. Mean urine output improved from 28 ml/hr to 90 ml/hr after decompressive laparotomy. The mean Ivy score was 443 +/- 34.95 ml/kg. Development of ACS in burn patients is associated with a high mortality. With development of IAH, therapeutic maneuvers such as sedation and paralysis, escharotomies, or changes in fluid management can be performed in hopes of altering the evolution of intra-abdominal hypertension to ACS. In patients with >40% TBSA burns, bladder pressures should initially be measured every 6 hours. When the Ivy score reaches 200 ml/kg, measure bladder pressures hourly. Decompressive laparotomies should be performed in all patients with ACS if less-invasive maneuvers fail.

The first three contributions addressed the problem of designing plasmid vectors for the expression of foreign proteins in E. coli. All three used the principle that, to reduce the genetic and metabolic load to the cell, low or moderate copy-number plasmids should be used, and in two cases higher copy numbers were induced late in the growth phase. Yarraiton (Celltech) reported on experiments to express calf met-prochymosin. Initial experiments with the high copy ampicillin-resistance plasmid (based on pAT153) using a trp promoter and T7 terminator gave 5% loss/generation which could not be stabilized by ampicillin selection during scale-up. Repressed levels of production even in the presence of the pSClOl par locus caused instability because the trp promoter was not fully repressed when it was on the high copy plasmid. Vectors were therefore constructed in which the primer RNAII transcription could be brought under control of various inducible promoters, in particular, bacteriophage P under the control of the Acl857 gene product. In the presence or the pSClOl par region these plasmids carrying the trp-controlled prochymosin gene were stable at 30°C in the absence of antibiotic selection, having a copy number of 5/genome.