Preparation and reactivity of an α-(difluoromethylene)-γ-lactone

3-(Difluoromethylene)-4,4-dimethyloxolan-2-one, prepared by difluoronethylenation of 4,4-dimethyloxolan-2,3-dione, exhibits marked reactivity toward nucleophilic reagents.     

Preparation of viologen polymers from alkylene dipyridinium salts by cyanide ion

Polymers of viologen structure were prepared by oxidation of quinoid polymers obtained by the dimerization of alkylene dipyridinium salts with cyanide ion as catalyst. These polymers showed the behavior of polyelectrolytes and redox polymers that turn a deep blue when reduced chemically or electrically.     

Directed 2-azonia-[3,3]-sigmatropic rearrangements. a convenient preparation of substituted 1-azaspiro[4,5]decanes

3-Acetylpyrrolidines are prepared from 5-methyl-5-vinyloxazolidines in a reaction which involves a directed 2-azonia-[3,3]-sigmatropic rearrangement.     

Highly efficient method for oxidation of alcohol with tert -butyl hydroperoxide catalyzed by diaryl diselenide

In the presence of a catalytic amount of diphenyl diselenide (0.1–0.2 eq) $\text{tert}$-butyl hydroperoxide oxidized benzylic and primary allylic alcohols in high yields. Saturated alcohols were alo cleanly oxidized by the use of bis(2,4,6-trimethylphenyl) diselenide.     

Optically active N-hydroxytartrimides for enantioselective peptide synthesis

Preparations of optically active N-hydroxytartrimides were achieved. 1,3,4-Trihydroxysuccinimide ester of Z-L-alanine and 1-hydroxy-3,4-diacetoxysuccinimide ester of Z-D-alanine were allowed to react with D,L-alaninate to produce L-L form and D-D form of Z-Ala-Ala-OEt respectively (optical yield 100%).     

Silyl-titanation of acetylenes and 1,3-dienes

A Ti^IIISi active species, Cp₂TiSiMe₂Ph, is formed either by the reaction of Cp₂TiCl₂ with two equivalents of PhMe₂SiLi or by the reaction of Cp₂TiCl with one equivalent of PhMe₂SiLi. Highly regio- and stereo-selective silyltitanation by this species has been observed with acetylenes and 1,3-dienes.     

Organofluorosilicates in organic synthesis: XV. Reaction of exo- and endo-5-norbornen-2-ylsilyl derivatives with n-bromosuccinimide. Difference in reactivity between hexacoordinate and tetracoordinate silicon compounds

The reactions of potassium 5-norbornen-2-ylpentafluorosilicate (I) and 5-norbornen-2-yltrimethylsilane (II) with NBS were examined. The former reaction gave 3-nortricyclyl bromide (IV) as the only detectable product, arising from the carbon—silicon bond cleavage. The latter reaction, however, gave 3-bromo-1-nortricyclyltrimethylsilane (V) as the major product, resulting from cleavage of the carbon—hydrogen bond α to silicon, together with IV and an unidentified product. GLC-monitoring of the reactions showed the higher reactivity of the norbornenyl derivative having the leaving group in theendo position irrespective of whether the leaving group is SiF₅ or H. Since no inhibition was observed by the addition of hydroquinone in the dark, the reactions have been regarded as homoallylic electrophilic substitutions. A concerted mechanism seems to be consistent with the experimental data. Cleavage of 1-nortricyclyltrimethylsilane by iodine monochloride to give 1-iodonortricyclene has also been studied.     

483—Monitoring cell potential of Escherichia coli with use of an electrode sensitive to tetraphenyl phosphonium: Change by addition of various sugars

An electrode sensitive to tetraphenyl phosphonium cation (TPP⁺) was applied to the determination of the membrane potential of E. coli (strain B, IAM 1268). This strain did not require EDTA (ethylenediamine tetraacetic acid)-treatment for accumulation of TPP⁺. As reported previously, some part of the TPP⁺-uptake was due to the binding to cell envelopes. The time course of TPP⁺-uptake by cells on addition of sugars was analysed, and the result indicated that the additional binding of TPP⁺ no longer occured. The change in the membrane potential on addition of various sugars was evaluated.