One‐Pot Cannizzaro Cascade Synthesis of ortho‐Fused Cycloocta‐2,5‐dien‐1‐ones from 2‐Bromo(hetero)aryl Aldehydes

An intramolecular Cannizzaro‐type hydride transfer to an in situ prepared allene enables the synthesis of ortho‐fused 4‐substituted cycloocta‐2,5‐dien‐1‐ones with unprecedented technical ease for an eight‐ring carboannulation. Various derivatives could be obtained from commercially available (hetero)aryl aldehydes, trimethylsilylacetylene, and simple propargyl chlorides in good yields.     

Shock-bubble interactions : Generation and evolution of vorticity in two-dimensional supersonic flows

We present high resolution simulations with the PPM code of shock-bubble interactions coresponding to the recent Haas-Sturtevant experiments. VCR cinemas show and diagnostic interpretations quantify the variety of shock-vortex interactions     

Fullerene-templated synthesis of a cyclic porphyrin trimer using olefin metathesis

An olefination approach to the construction of covalently linked cyclic metalloporphyrin trimers is presented using fullerenes such as C(60) or C(70) as a template. Yields of the trimer approach 60%. In the absence of a template, the major product is the cyclic dimer (50% yield) with only a small amount of trimer (<10%) formed, indicating this is a template-directed approach.     

Killing time

Theoretical consequences of the gravitational origin of inertial reaction forces, that is, Mach's principle, are explored. It is argued that Mach's principle leads to the conclusion that time, as we normally treat it in our common experience and physical theory, is not a part of fundamental reality; the past and future have a real, objective existence, as is already suggested by both special and general relativity theory. A laboratory scale experiment whereby Mach's principle, and thus radical timeless ness, can be established is mentioned.     

Investigations into the utility of high-surface area silica pellets as potential solid-phase synthesis supports

Grace-Davidson silica pellets (SMR-057-015) are found to be optimal for surface grafting of (RO)₃Si(CH₂)₃FG reagents. While loadings of up to 2.1 mmol g⁻¹ can be attained (ca. 0.05 mmol per pellet) access of further reagents to the graft sites is problematic above loadings of 0.8 mmol g⁻¹. ¹³C CPMAS NMR studies may be carried out on individual pellets (using natural abundance substrates) and the resulting spectra are diagnostic in identifying successful subsequent coupling reactions.     

Intermediate coupling model description of55Fe and57Fe

The properties of the negative parity states of⁵⁵Fe and⁵⁷Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states.     

Chain folding in poly-trans-1,4-butadiene crystals grown from various solvents

Crystals of poly-trans-1,4-butadiene of uniform size have been grown from three solvents (n-heptane, methyl isobutyl ketone, and toluene) by using a minimum dissolution temeprature technique. The percentage of double bonds available for reaction in the crystals was determined by epoxidation in suspension; crystal thicknesses were measured by electron microscopy. These values were used to calculate the number of monomer units per fold. The number of available double bonds was found to increase with decreasing molecular weight, evidence for the presence of non-reentrant chains (cilia) at the crystal surfaces. The nature of the chain fold in poly-trans-1,4-butadiene crystals is discussed.