G. Balavoine

Synthesis and some reactions of ferrocenylacetylenes

Abstract The conversion of acetylferrocene or diacetylferrocene into ethynylferrocene 1 or diethynylferrocene 4, respectively, is achieved in good yield in a one-pot synthesis using Negishis reagent. The diethynylferrocene is isolated as its trimethylsilyl derivative 5. The complexes 1 and 5 undergo various nucleophilic substitution reactions, resulting in new ferrocenyl derivatives.

Cyclopalladated 2-t-butyl-4,4-dimethyl-2-oxazoline : its preparation, and use in the functionalisation of a non-activated carbon-hydrogen bond

Abstract Activation and functionalisation of one of the methyl groups of pivalic acid can be achieved through cyclopalladation of its 4,4-dimethyloxazoline derivative. This reaction gives a separable mixture of dinuclear and trinuclear species. The dimeric complex undergoes insertion of methyl vinyl ketone and of carbon monoxide, but is alkylated by aliphatic iodides, thereby providing a new route to homologated tertiary carboxylic acids.

Synthesis and nonlinear optical properties of new bimetallic iron/palladium complexes

Abstract Two new ferrocenyl derivatives, ( z )-[1-(benzylthio)-1-(4′,4′-dimethyl-oxazolinyl)-2-ferrocenyl]ethylene ( 3 ) and ( Z )-[1-(benzylsulfino)-1-(4′,4′-dimethyloxazolinyl)-2-ferrocenyl]ethylene ( 4 ) have been synthesized. On complexation with PdCl 2 these yield new bimetallic complexes 5 and 6 respectively. Non-linear optical properties measured by the EFISH technique show an enhanced molecular hyperpolarizability upon complexation, leading to higher values for β 0 .

Can circularly polarized light be used to obtain chiral compounds of high optical purity

SummaryThe production of optically active compounds starting from optically inactive material and with the help only of circularly polarized light is briefly discussed. This problem is possibly related to the appearance of optical activity on earth. Some aspects of photochemical asymmetric synthesis of helicenes are given, the optical yields being always lower than 1%. The possibility of obtaining much higher optical purity by using partial asymmetric photodecomposition of a racemic mixture is then discussed. The kinetic treatment allows the prediction that at the end of the destruction the recovered material must be of high optical purity. An experimental demonstration of the correctness of the calculations is shown in the case of dl camphor. Camphor of 20% optical purity could be isolated after prolonged photolysis by circularly polarized light.

Palladium-catalyzed reaction of tributyltin hydride. Selective and very mild deprotection of allyl and allyloxycarbonyl derivatives of amino-acids.

Abstract Allyl(All) and Allyloxycarbonyl(Alloc) amino-acid derivatives are deprotected through palladium-catalyzed hydrostannolysis by Bu 3 SnH in a highly selective manner. Benzyl and benzyloxycarbonyl groups are stable under these conditions. Moreover the allyl and Alloc groups seem orthogonal to the t-butyl and t-butoxycarbonyl protecting groups.

Synthesis, catalytic activity and the molecular structure of (μ3-CCH3)Co3(CO)7-μ-(Ph2PCH2PPh2)

Abstract Reaction of (μ3-CCH3)CO3(CO)9 (I) with dppm (dppm = bis-(diphenylphosphino)methane) affords the cluster (μ3-CCH3)Co3(CO)7-dppm (II). The crystal and molecular structure of II have been determined at −160°C. The dppm ligand bridges one of the three metal—metal edges in the equatorial plane to give a five-membered ring, which adopts an envelope conformation. Cluster II functions as a catalyst for the hydroformylation of 1-pentene (80 bar of H2/CO (1/1); 110°C). The results indicate that the dppm bridging ligand stabilizes and activates the cluster for catalysis, and open the way to the synthesis of chiral clusters.

Structure cristalline du complexe [FeCp((-)DIOP)I] analyse conformationnelle du cycle de chelation de la (-)diop

Abstract The crystal structure of [FeCp((-)diop)I] has been determined by x-ray analysis and refined by least squares methods to R = 0.091 for 1603 independent reflections. The complex crystallises in the orthorhombic space group P212121 with a unit cell of dimensions a = 16.920 (3), b = 19.902(4), c = 10.649(6)». The conformation of the chelated (-)DIOP is analysed and compared with those occuridng in other complexes of known structures.

Selective oxidation of saturated hydrocarbons using an electrochemical modification of the gif system.

Abstract The Gif system for selective hydrocarbon oxidation can be carried out replacing the zinc by a cathodic electrochemical reduction; the yields obtained and the selectivities observed are very similar.

Rearrangements d'allyloxy-pyridines catalyses par les complexes du platine(o)

Abstract Zerovalent Platinum complexes catalyse the conversion of allyloxy-pyridines into N-allyl pyridones. The results can be rationalized by assuming an intermediate π allylic complex.

Thioglycosides as Potential Glycosyl Donors in Electrochemical Glycosylation Reactions. Part 2: Their Reactivity Toward Sugar Alcohols.

Abstract Constant potential electrolysis of the glycosyl donors p-methylphenyl 2,3,4,6-tetra-O-benzyl-1-thio-β-D-glucopyranoside (1) and p-methylphenyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (4) in dry acetonitrile in the presence of various primary and secondary sugar alcohols, performed in an undivided cell, gave β-linked disaccharide derivatives selectively in good yields. Oxidative coupling of p-methoxyphenyl 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside (2 1) with p-methoxybenzyl 4,6-O-benzylidene-2-deoxy-2-phthalimido-β-D-glucopyranoside (16) gave selectively the α-linked disaccharide 22 in good yield.