A concise synthesis of 2-benzoyl-1-indanones and 1-indanones from 2-aryl-1-tetralones

Abstract

Methyl-2-(3-oxo-3-aryl) benzoates derived from acid catalyzed air oxidative fragmentation of 2-aryl-1-tetralones were efficiently undergone intramolecular-Claisen condensation in the presence of potassium tertiary butoxide. The resulting 2-benzoyl-1-indanones formed in two-step ring contractions were further subjected to indium triflate mediated retro-Claisen condensation to get 1-indanones.     

Heterometallic Triply‐Bridging Bis‐Borylene Complexes

Triply‐bridging bis‐{hydrido(borylene)} and bis‐borylene species of groups 6, 8 and 9 transition metals are reported. Mild thermolysis of [Fe₂(CO)₉] with an in situ produced intermediate, generated from the low‐temperature reaction of [Cp*WCl₄] (Cp*=η⁵‐C₅Me₅) and [LiBH₄?THF] afforded triply‐bridging bis‐{hydrido(borylene)}, [(μ₃‐BH)₂H₂{Cp*W(CO)₂}₂{Fe(CO)₂}] ( 1 ) and bis‐borylene, [(μ₃‐BH)₂{Cp*W(CO)₂}₂{Fe(CO)₃}] ( 2 ). The chemical bonding analyses of 1 show that the B?H interactions in bis‐{hydrido (borylene)} species is stronger as compared to the M?H ones. Frontier molecular orbital analysis shows a significantly larger energy gap between the HOMO‐LUMO for 2 as compared to 1 . In an attempt to synthesize the ruthenium analogue of 1 , a similar reaction has been performed with [Ru₃(CO)₁₂]. Although we failed to get the bis‐{hydrido(borylene)} species, the reaction afforded triply‐bridging bis‐borylene species [(μ₃‐BH)₂{WCp*(CO)₂}₂{Ru(CO)₃}] ( 2′ ), an analogue of 2 . In search for the isolation of bridging bis‐borylene species of Rh, we have treated [Co₂(CO)₈] with nido‐[(RhCp*)₂(B₃H₇)], which afforded triply‐bridging bis‐borylene species [(μ₃‐BH)₂(RhCp*)₂Co₂(CO)₄(μ‐CO)] ( 3 ). All the compounds have been characterized by means of single‐crystal X‐ray diffraction study; ¹H, ¹¹B, ¹³C NMR spectroscopy; IR spectroscopy and mass spectrometry.     

Copper-catalyzed hydrostannation of activated alkynes

[reactions: see text] [(Ph3P)CuH]6 effectively catalyzes the hydrostannation of activated alkynes with exclusive regioselectivity for alpha-stannation. Syn hydrostannation is observed exclusively for alkynoates. Anti or syn hydrostannation adducts are obtained as products for alkynone substrates.     

Complex series [Ru(tpy)(dpk)(X)]n+ (tpy = 2,2':6',2''-terpyridine; dpk = 2,2'-dipyridyl ketone; X = Cl-, CH3CN, NO2(-), NO+, NO*, NO-): substitution and electron transfer, structure, and spectroscopy

The complex framework [Ru(tpy)(dpk)]2+ has been used to study the generation and reactivity of the nitrosyl complex [Ru(tpy)(dpk)(NO)]3+ ([4]3+). Stepwise conversion of the chloro complex [Ru(tpy)(dpk)(Cl)]+ ([1]+) via [Ru(tpy)(dpk)(CH3CN)]2+ ([2]2+) and the nitro compound [Ru(tpy)(dpk)(NO2)]+ ([3]+) yielded [4]3+; all four complexes were structurally characterized as perchlorates. Electrochemical oxidation and reduction was investigated as a function of the monodentate ligand as was the IR and UV-vis spectroscopic response (absorption/emission). The kinetics of the conversion [4]3+/[3]+ in aqueous environment were also studied. Two-step reduction of [4]3+ was monitored via EPR, UV-vis, and IR (nu(NO), nu(CO)) spectroelectrochemistry to confirm the {RuNO}7 configuration of [4]2+ and to exhibit a relatively intense band at 505 nm for [4]+, attributed to a ligand-to-ligand transition originating from bound NO-.     

Conservation of a prey-predator fishery with predator self limitation based on continuous fishing effort

The paper deals with the problem of selective harvesting in a prey-predator model with predator self limitation. Criteria for local stability and global stability for both the exploited and unexploited system are derived. The effort has been considered as a dynamic variable and taxation as a control instrument to protect the fish populations from over exploitation. Finally, the optimal taxation policy is discussed with the help of control theory.     

Impact of network topology on cationic diffusion and hardness of borate glass surfaces

The connection between bulk glass properties and network topology is now well established. However, there has been little attention paid to the impact of network topology on the surface properties of glass. In this work, we report the impact of the network topology on both the transport properties (such as cationic inward diffusion) and the mechanical properties (such as hardness) of borate glasses with modified surfaces. We choose soda lime borate systems as the object of this study because of their interesting topological features, e.g., boron anomaly. An inward diffusion mechanism is employed to modify the glass surface compositions and hence the surface topology. We show that accurate quantitative predictions of the hardness of the modified surfaces can be made using topological constraint theory with temperature-dependent constraints. Experimental results reveal that Ca(2+) diffusion is most intense in glasses with lowest BO(4) fraction, whereas Na(+) diffusion is only significant when nonbridging oxygens start to form. These phenomena are interpreted in terms of the atomic packing and the local electrostatic environments of the cations.     

Ferromagnetically coupled cobalt-benzene-cobalt: the smallest molecular spin filter with unprecedented spin injection coefficient

Here, we predict that the ferromagnetically coupled cobalt-benzene-cobalt system will act as the smallest molecular spin filter with unprecedented spin injection coefficient. To validate our in-silico observation, we have performed state-of-the-art nonequilibrium Green's function calculations and analyzed the density of states of cobalt at the relativistic and nonrelativistic level of theory. Remarkably, we found that unpaired 3d electrons of cobalt are not participating in the spin transport process like other transition metal containing multidecker complexes. Instead, an admixture of the outer-sphere 4s and 4p orbitals of cobalt along with the 2p orbital of carbon of the benzene moiety is contributing to the singly occupied highest molecular orbital in the majority spin channel that creates a path for coherent spin transport leading to the extremely high spin injection coefficient of the system. The absence of the 3d electrons of cobalt in the spin transport process has been carefully examined, and it was found that the nodal structure of the 3d orbital of cobalt is not at all suitable for bonding in the cobalt-benzene-cobalt system. The whole study indicates that the underlying mechanism of the spin filter action in cobalt-benzene-cobalt is completely distinctive from the other known materials.     

Analysis of the reactivities of protein C-H bonds to H atom abstraction by OH radical

Ab initio and density functional theory calculations are used to monitor the process wherein a OH· radical is allowed to approach the various CH groups of a Leu dipeptide, with its CH(2)CH(CH(3))(2) side chain. After forming an encounter complex, the OH· abstracts the pertinent H atom, and the resulting HOH is then dissociated from the complex. The energy barriers for H· abstraction from the β, γ, and δ CH groups are all less than 8 kcal/mol, but a significantly higher barrier is computed for the C(α)H removal. This higher barrier is the result of the strong H-bonds formed in the encounter complex between the OH· and the NH and C═O groups of the peptide units that surround the C(α) atom. This low-energy complex represents a kinetic trap which raises the energy needed to surmount the ensuing H· transfer barrier.