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Palladium-catalyzed acryloxylation of several cycloalkenes in the presence of the Pd(OAc)(2)/p-benzoquinone/MnO2 catalytic system is reported. This oxidation reaction yields allylic acrylates as the sole products through the intermediacy of an eta(3)-ally

o-Bromostyrenes 2-Br react with various alkenes in the presence of palladium catalysts to give either substituted indene 6 or o-diethenylbenzene derivatives 3, depending on the reaction conditions. Under oxidative conditions the latter can be cyclized to indene derivatives as well.

We describe an original QSPR model called the EVM model (Energy, Volume, Mass) to calculate the glass transition temperature (Tg) of aliphatic acrylate and methacrylate homopolymers using classical molecular mechanics and dynamics. The latter was used to calculate an energy density function related to the cylindrical volume of a 20 monomer unit polymer segment (TSSV, Total Space around a Standard deviation Volume). We then calculated the Tg as a function of this density function and the repeat unit molecular weight, although no interchain interactions were taken into account. For linear and branched aliphatic acrylate and methacrylate polymers, the standard deviation from linear regression was 12 K, and the r2 was 0.96. The model allows calculation of the Tg with an average absolute error of error of 10% for linear and branched derivatives not included in the original linear regression analysis. The results obtained with the EVM model are compared with those obtained with Bicerano's model. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2579–2590, 1997

The reaction of phenalenone with various sulphur-derived nucleophiles gave 1-hydroxy-9-alkyl- or -aryl-thiophenalenes. The complexity of the aromatic 1H and 13C signals does not allow straightforward assignments. These were rendered possible by the use of two-dimensional 1H-detected heteronuclear one-bond (HMQC) and multiple-bond (HMBC) correlation techniques.

Ruthenium tetroxide generated in situ under the Sharpless conditions was applied to different hydrocarbons containing cyclopropane groups either spiroanellated or ring-fused. In all cases oxidation occurred exclusively at the positions α to the cyclopropyl group to give ketones. Ring cleavage was observed when such positions were tertiary.

Described here is a QSPR equation for calculating glass transition temperatures for acrylate and methacrylate polymers, especially those with bulky ester substituents. This approach is based on molecular mechanics calculations and exclusively involves a force field to describe a particular polymer system; i.e., no group additivity values are required. Results from two different force fields yielded similar results, indicating that this model is not dependent on a particular force field parameter set but rather on the atomic properties that the force field describes. The molecular mechanics calculation results (energy term), the repeat unit mass, and a measure of the volume surrounding the polymer segment (TSSV) were used to determine an energy density function that is related to experimental Tg values. This energy density function is important because it illustrates that the glass transition temperature of an amorphous polymer is related not only to the volume surrounding the polymer segment but also to i...

Bidentate ligands featuring two different nitrogen heterocycles (pyridine, oxazoline, oxazolidine and thiophene) directly linked together or separated by a spacer, have been prepared and used as ruthenium ligands to epoxidize trans -stilbene and to study the competition between this reaction and oxidative cleavage of the double bond.

The reaction of gem-dihalogenocyclopropanes derivatives with (tetracarbonyl)(methoxycarbonylato)ferrate(I−) has been investigated; gem-dibromocyclopropanes and gem-chlorobromocyclopropane derivatives are reduced and carbonylated. It could be shown that a bromo ester such as methyl 1-bromo-2-phenylcyclopropanecarboxylate is an intermediate in the transformation of 1,1-dibromo-2-phenylcyclopropane into methyl cis- and trans-2-phenylcyclopropanecarboxylates and dimethyl 2-phenyl-1,1-cyclopropanedicarboxylate.

Starting from natural (−)-sclareol (4,) (+)-amberketal (9) and (−)-epi-8-amberketal (10) have been synthesized regioselectively in 4 (24% overall yield) and 5 steps (7% overall yield) respectively, by passing through the same unpurified key intermediate 7b.

The interaction of phenalenonc and 2-methylindole in presence of stoechiomctric amounts of paratoluenesulfonic acid in methanol under argon, yields twelve compounds which have been spectroscopically characterised. Seven compounds or sets of compounds could be scpareted by flash chromatography. Phenalene 4. and phenalanone 8 result from a disproportionalion reaction of a key intermediate 18. 2-Methylindolylphenalene 5 and bis(2-methyl)indolylphenalene 6 and 7 exist under the form of a complex mixture of lauiomers. 2-Methylindolylphenalanones 9 and 10. 2-methylindolylphenalenones 11. 12. 1 3. and bis(2-methylindolyl)phenalenones 14 and 15. could also be isolated from the reaction mixture. In presence of air and light compounds 5, 6, and 7. oxidize into 11, 12, 13, 14, and 15 via the corresponding phenalenyl radical. The mechanism of formation and interconversion of these products is discussed and experimentally supported. The peculiar reactivity of the phenalenic derivatives is analysed and it is s...

We describe an unusual [2+2+2] MIMIRC reaction between a lithium dienolate 6 and methyl acrylate. The more classical double Michael addition cyclisation provides an efficient entry towards key intermediate 5 for 2-isocyanopupukeanane 1 synthesis.

We describe the synthesis and reactivity of new mononuclear copper(I) complexes 4a–c, which can be considered to be copper monooxygenase models and can be used to achieve hydroxylation of aliphatic C–H bonds by dioxygen activation.

Starting from natural (−)-sclareol (4,) (+)-amberketal (9) and (−)-epi-8-amberketal (10) have been synthesized regioselectively in 4 (24% overall yield) and 5 steps (7% overall yield) respectively, by passing through the same unpurified key intermediate 7b.

Acrylic and methacrylic esters can be obtained in one step from alkenes using a Pd(OAc)2/benzoquinone/MnO2 catalyst; with acrylic acid and a suitable alkene, it is also possible to obtain α-methylene γ-lactones in one step.

The reaction of gem-dihalogenocyclopropanes derivatives with (tetracarbonyl)(methoxycarbonylato)ferrate(I−) has been investigated; gem-dibromocyclopropanes and gem-chlorobromocyclopropane derivatives are reduced and carbonylated. It could be shown that a bromo ester such as methyl 1-bromo-2-phenylcyclopropanecarboxylate is an intermediate in the transformation of 1,1-dibromo-2-phenylcyclopropane into methyl cis- and trans-2-phenylcyclopropanecarboxylates and dimethyl 2-phenyl-1,1-cyclopropanedicarboxylate.

We describe the synthesis of nor-norambracetal 13 from sclareol 1 , using γ-homobicyclo-farnesylic alcohol 3 as a key intermediate.

As phenalene is an alternant hydrocarbon it is oxidized very easily to phenalenone, which condenses with various nitrogen nucleophiles in the presence of p-toluenesulphonic acid. 2-Methylindolylphenalene is obtained with 2- methylindole, together with other products. This product is a mixture of five tautomers in equilibrium, and these were analysed by homo- and heteronuclear two-dimensional high-field NMR (500 MHz) spectroscopy.

We describe an unusual [2+2+2] MIMIRC reaction between a lithium dienolate 6 and methyl acrylate. The more classical double Michael addition cyclisation provides an efficient entry towards key intermediate 5 for 2-isocyanopupukeanane 1 synthesis.

Water-soluble ligands are synthesized by quaternization of tertiary aminophosphine with either hydrochloric acid or methyl iodide. The use of these ligands in the biphasic palladium-catalyzed telomerisation of butadiene, produces 1-methoxy-2,7-octadiene with 78% selectivity and conversions ranging from 52 to 79%. Conversion and selectivity are little altered on catalyst recycling. Telomerisation of isoprene is somewhat less satisfactory, with a conversion not higher than 52%.

Reductive carbonylation of a gem-dibromo cyclopropane to carbomethoxycyclopropane can be achieved with excess Fe(CO) 5 in DMF and an added nucleophile such as MeOH or MeONa.

The synthesis is reported of a binuclear copper(I) complex 2 which exhibits the catalytic phenolase and catecholase activity of tyrosinase.

Bicyclo[3.2.1]octan-3-one solvent: 400 ml. of petroleum ether intermediate: exo-3,4-dichlorobicyclo[3.2.1]oct-2-ene intermediate: 3-chlorobicyclo[3.2.1]oct-2-ene product: bicyclo[3.2.1]octan-3-one Keywords: hydrolysis, miscellaneous; reduction, CX CH; norbornene, preparation of

We describe the synthesis and reactivity of new mononuclear copper(I) complexes 4a–c, which can be considered to be copper monooxygenase models and can be used to achieve hydroxylation of aliphatic C–H bonds by dioxygen activation.

The reactivity of the so-called unactivated hydrocarbons is of current interest from the theoretical, experimental and industrial points of view, in the areas of chemistry and biochemistry. Two different categories of substrates are part of class of unactivated hydrocarbons: saturated alkanes and aromatic hydrocarbons. Quite interestingly, the C-H bond energy of the former (102 kcal/mole) is lower than the latter (110 kcal/mole). The activation process by transition metal-complexes requires some kind of association step and can eventually be visualized as an oxidative addition of a C-H bond to an electrophilic metallic species (Fig. 1). The most efficient strategy for C-H bond activation should therefore combine an increase of the electron density in the C-H σ* orbitals (which requires nucleophiles) and a decrease of the electron density in the C-H σ orbital (which requires electrophiles, for instance super acids or low-valent metal complexes of Ru, Ir, Rh, Re).1 This combination can efficiently be achieved in radicals or high-valent metal complexes such as highly electrophilic metal oxo species (which can formally act as oxene sources). The occurrence and reactivity of such reactive intermediates has been clearly demonstrated in iron porphyrin complexes of the CP-450 family.2

The intramolecular carboxypalladation reaction [Pd(OAc) 2 5 mol %, NaOAc 2 eq, O 2 , THF, rt] of 2-(2-Cycloalken-1-yle) propenoic acids yields ring fused α-methylene γ-butyrolactones with good yields (75–80%).

We describe the synthesis of nor-norambracetal 13 from sclareol 1 , using γ-homobicyclo-farnesylic alcohol 3 as a key intermediate.

Ambraketal 7 and epiambraketal 8 are synthesized efficiently from sclareol 1. The key intermediate 5 is obtained by a regioselective elimination of ketoacetate 4 resulting from the side chain oxidative degradation of 1 by ruthenium tetroxide generated in situ .

We describe the synthesis of norambracetal 14 from sclareol 1 using γ -homobicyclofarnesilic aldehyde1O as a key intermediate.

Participation of polar neighboring groups in the epoxide ring opening of functionalized norbomanes modifies the course of the tandem ruthenium-catalyzed rearrangement/oxidation usually observed with norbomane epoxides and provides an entry into regio and stereoselectively functionalized norbomane derivatives.

A protection-deprotection sequence is used in order to control the formation of the exocyclic double bond of compound 10 which is further used for the synthesis of the title compounds.

The nature of the reoxiding reagent plays a decisive role in the outcome of the ruthenium-catalyzed oxidation of 2,3-epoxynorbornane.

Oxidation of bridged polycyclic alkanes with in situ generated RuO4 occurs by a concerted mechanism involving interaction of the highly electrophilic oxoruthenium species with tertiary unhindered C–H bonds.

Acrylic and methacrylic esters can be obtained in one step from alkenes using a Pd(OAc)2/benzoquinone/MnO2 catalyst; with acrylic acid and a suitable alkene, it is also possible to obtain α-methylene γ-lactones in one step.