Tatsuo Fujinami

Samarium(II) di-iodide induced reductive coupling of α,β-unsaturated esters with carbonyl compounds leading to a facile synthesis of γ-lactone

Samarium(II) di-iodide, which is a strong one-electron transfer reducing agent, is effective for the reductive coupling of α,β-unsaturated esters with carbonyl compounds, whereby substituted γ-lactones can easily be prepared in good to excellent yields under very mild conditions. Two mole equiv. of samarium(II) di-iodide to each mole equiv. of starting substrate always give reasonable yields. The presence of an alcohol is essential in the reaction, complex unidentified products being formed in the absence of an alcohol; t-butyl alcohol gave more satisfactory results than methanol and ethanol. The alcohol acts as a proton donor, the use of MeOD leading to a deuteriated γ-lactone. The reaction is applicable to both aliphatic and aromatic ketones or aldehydes, whereas the electrochemical method is limited to aliphatic substrates. The diastereoselectivity is examined in the reaction of 4-t-butylcyclohexanone with ethyl acrylate; an anti-isomer is produced predominantly (syn :anti= 1 : 9) as the result of selective axial attack. The reaction may proceed by a radical mechanism, and reaction may not involve a samarium ester homoenolate. The reaction is extended to the intramolecular reaction of an α,β-unsaturated keto ester (8-oxonon-2-enoate) leading to the ready synthesis of a bicyclic γ-lactone.

The use of boroxine rings for the development of high performance polymer electrolytes

Abstract Boroxine ring containing additives, Bx( n )=B 3 O 3 [O(CH 2 CH 2 O) n CH 3 ] 3 , were found to be compatible with a wide variety of polymer hosts. Polymer electrolytes exhibiting room temperature conductivities of up to 10 −5 S cm −1 were obtained by incorporation of Bx( n ) and LiCF 3 SO 3 into poly(methyl methacrylate) and propylene oxide–ethylene oxide co-polymers. Polymers composed of inter-connecting networks of boroxine rings were also investigated as suitable hosts for the boroxine additives B 3 O 3 [O(CH 2 CH 2 O) n CH 3 ] 3 . Poly(methyl methacrylate) systems exhibited an electrochemical stability window in the region of 4.9 V, while transference number measurements indicated high Li + ion conductivity.

Novel lithium salts exhibiting high lithium ion transference numbers in polymer electrolytes

Abstract A variety of lithium aluminates containing two oligoether groups and two electron-withdrawing groups, CF 3 CO 2 , CF 3 SO 3 , (CF 3 SO 2 ) 2 N or C 6 F 5 O, on aluminum atom were prepared. Viscous liquid salts were obtained by incorporation of oligoether substituents containing an average of 7.2 and 11.8 ethylene oxide repeating units. Ionic conductivity of the liquid salt was enhanced by incorporation of electron withdrawing groups on the aluminate center and was dependent on the chain length of oligoether groups. Temperature dependence of ionic conductivity was well fitted to Vogel–Tammann–Fulcher equation, indicating that ion motion was coupled to segmental motion of oligoether chains. Polymer electrolytes were prepared by mixing of the salt and poly(ethylene oxide) and exhibited a high ionic conductivity, a high lithium transference number, a wide potential window, and a good thermal stability.

Boroxine ring containing polymer electrolytes

Abstract Anion trapping polymer electrolytes incorporating boroxine (B 3 O 3 ) rings and oligoether side chains have been demonstrated to combine high Li + ion transference numbers, thermal stability and an electrochemical stability window in the region of 4.9 V. Ionic conductivities of up to 1.6×10 −5 S cm −1 at 30°C and which exhibit Volger–Tamman–Fulcher (VTF) behaviour have been observed.

Preparation and electrochemical properties of palladium(0) complexes coordinated by quinones and 1,5-cyclooctadiene

The complexes Pd(quinone)(COD) (COD = 1,5-cyclooctadiene) are prepared by a ligand substitution reaction of Pd2(DBA)3 (DBA = dibenzylideneacetone) in the presence of both quinone and COD. Palladium(0) complexes coordinated by quinones only are formed in the reaction in the absence of COD. The cyclic voltammetric behavior of Pd(quinone)(COD) has been studied. The reduction potentials for quinones shifted toward negative values on coordination to palladium(0). The oxidation potentials for the central palladium(0) in Pd(quinone)(COD) depend on the electron-withdrawing ability of the free quinones, and are in the following series: quinone = p-benzoquinone < 5,8-dihydro-1,4-naphthoquinone ∼ 1,4-naphthoquinone < duroquinone. The shift of oxidation potentials for Pd(quinone)(COD) on changing the quinones as ligands is in contrast to that of Pd(quinone)(triphenylphosphine)2.

Molecular design of inorganic-organic hybrid polyelectrolytes to enhance lithium ion conductivity

Abstract Three types of inorganic–organic hybrid polymers containing the ate complex structure (e.g. aluminate, borate) were prepared as lithium ion conducting polymer electrolytes. The relationship between polymer structure and ionic conductivity was discussed from which it was shown that the concepts of molecular design used were very important. Ionic conductivity was enhanced by the introduction of Lewis acid groups, which reduced the charge density on the ate complex and weakened ion pairing between the lithium ion and the immobilized anion. Ionic conductivity was found to be dependent on the length and structure of the oligoether chain. In addition, introduction of bulky groups onto the polymer backbone in the region of the oligoether chain restricted the mobility of the latter.

Novel inorganic–organic polymer electrolytes – preparation and properties

Abstract Anion trapping polymer electrolytes were prepared from polymer hosts incorporating boroxine rings and pendant oligoether side chains. The materials exhibited high Li + transference numbers and high ionic conductivity. Evidence for anion interaction with the boroxine ring was obtained from solid 11 B-NMR spectroscopy.

1,2-Regioselective reduction of α,β-unsaturated carbonyl compounds with lithium aluminium hydride in the presence of lanthanoid salts

An α,β-unsaturated carbonyl compound when reduced by lithium aluminium hydride in the presence of lanthanoid chloride, bromide, iodide, or acetylacetonate gives, selectivity, an allylic alcohol, while in its absence saturated alcohol formation predominates. Such reactions can be applied to various α,β-unsaturated carbonyl compounds such as aldehydes, ketones, esters, and lactones. In addition to its wide applicability, this reagent appears to be easier to use, than other known reducing reagents.

Synthesis and characterization of aluminate polymer electrolytes and their blends with poly(ether)s

Abstract A series of single ion conducting aluminate polymer electrolytes were synthesized and their blends with poly(ether)s characterized. A great improvement of mechanical properties and processability was obtained upon blending with poly(ethylene oxide) or an ethylene oxide–propylene oxide copolymer. Enhancement of the ionic conductivity of blended polymer electrolytes was observed by adding LiCF 3 SO 3 and cationic transference numbers were determined to be about 0.56.

Intramolecular reductive cyclization of unsaturated keto- or aldo-esters by samarium(II) di-iodide: a ready synthesis of bicyclic γ-lactones

Treatment of unsaturated keto- or aldo-esters with Sml2 in tetrahydrofuran (THF) or THF–hexamethylphosphoramide affords bicyclic γ-lactones in moderate to good yields.