Reaction of carbon dioxide with a bimetallic octadienylbridged palladium complex

Reaction of equimolar amounts of μ-1–3-η:6–8-η-octadienatobis(1,1,1,5,5,5-hexafluoroacetylacetonatopalladium) and triisopropylphosphine gives a bimetallic octadienyl-bridged complex, in which one palladium atom is η¹ -bound to the terminal carbon of the octadienyl chain. Insertion of CO₂ into this PdC bond gives a carboxylate complex; acidic decomposition and hydrogenation of the carboxylate complex gives pelargonic acid. The results are discussed in relation to the mechanism of the palladium-catalyzed reaction between butadiene and carbon dioxide.     

Norbornanes. Part 21. Bridging strain in norbornyl and oxanorbornyl cations

Further evidence is presented that the 2-norbornyl cation is stabilized primarily by C(2)–C(6) bridging, and that C(2)–C(7) bridging leads to prohibitive strain. Thus, a comparison of the heats of hydrogenation of nortricyclene 17 and bicyclo[3. 2. 0. 0.^2,7]heptane 18 indicates that the strain energy of the latter is ca. 21.5 kcal/mol higher that that of 17 . Furthermore, 6-exo-2-oxabicyclo[2. 2. 1]heptyl sulfonates 8 ionize with strong O(2) participation to the bridged oxonium ion 12. In contrast, 2-endo-7-oxabicyclo[2.2.1]heptyl sulfonates 11 ionize without O(7) participation to form the unbridged carbenium ion 15 .     

Inductivity and charge dispersal in quinuclidinium and bicyclo[2.2.2]octyl-1-cations

The pK_a of 2-, 3- and 4-substituted quinuclidinium perchlorates and the solvolysis rates of the corresponding bicyclo[2.2.2]octyl-l-p-nitrobenzenesulfonates reveal the dispersal of charge in ammonium ions and carbocations.     

Regioselectivity of the metalation of polymethoxylated pivaloyl-aminobenzenes. Synthesis of methoxy-2(1H)-quinolones precursors of 2-substituted-5,8-quinolinediones

Synthesis of methoxy-2(1H)-quinolones precursors of 2-substituted-5,8-quinolinediones is described. A metalation, Heck coupling reaction and cyclisation sequence is used. Regioselectivity of the metalation of methoxypivaloylaminobenzenes is studied.     

Synthese und Basizität 4-heterosubstituierter. Chinuclidine Chinuclidinreihe, 13. Mitteilung

The preparation of several 4-heterosubstituted quinuclidines and the pK_a values of their hydroperchlorates in water are reported.     

Ergodicity for a weakly damped stochastic non-linear Schrödinger equation

We study a damped stochastic non-linear Schr?dinger (NLS) equation driven by an additive noise. It is white in time and smooth in space. Using a coupling method, we establish convergence of the Markov transition semi-group toward a unique invariant probability measure. This kind of method was originally developed to prove exponential mixing for strongly dissipative equations such as the Navier-Stokes equations. We consider here a weakly dissipative equation, the damped nonlinear Schr?dinger equation in the one-dimensional cubic case. We prove that the mixing property holds and that the rate of convergence to equilibrium is at least polynomial of any power.     

A Reexamination of Inductive Substituent Constants Derived from pKa Values of 4-Substituted Quinuclidines. Polar effects. Part VIII

pK_a Values of 42 quinuclidinium perchlorates I have been measured in 0.1 M aqueous KCl-solution. In a few cases small corrections of earlier thermodynamic pK_a values are indicated. These measurements, in conjunction with recent X-ray structure determinations, confirm the reliability of the inductive substituent constants σ_I^q derived from them.     

Nucleophilic Reactions at Tertiary Carbon. Part 2. σ- and π-routes to the 8-hydrindanyl cation

Stereoisomeric ion pairs are implicated as intermediates in the solvolysis of cis and trans-8-hydrindanyl chloride 3 , whereas 4-(cyclopenten-1-yl)butyl tosylate 5 appears to cyclize by way of an unsymmetrically solvated 8-hydrindanyl cation. This follows from the solvolysis products and rates of these compounds in aqueous solvents. The rate and equilibrium constants of the chlorides 3 show that the transition state for the trans-isomer is more stable by 0.5 kcal than the one for the cis-isomer. By inference the intermediates differ by a similar amount of energy. Experimental results are not explained satisfactorily by conformationally isomeric 8-hydrindanyl cations, as suggested in the literature.