- Tetraaryldisilanes as a novel strategic radical reagent
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Reactivity of 1,1,2,2-tetraaryldisilanes as a radical reagent in ethanol was studied in reduction of alkyl bromides, addition to olefins and alkylation onto heteroaromatic bases with alkyl bromides. The present organodisilanes showed moderate to good reactivities for these three types of radical reactions. Among some disilanes prepared, 1,1,2,2-tetraphenyldisilane is the most useful in view of its reactivity and ease of preparation.
- Yamazaki, Osamu,Togo, Hideo,Malsubayashi, Sou,Yokoyama, Masataka
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p. 3735 - 3747
(2007/10/03)
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- 1,1,2,2-tetraphenyldisilane as a diversified radical reagent
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Reactivity of 1,1,2,2-tetraphenyldisilane as a radical reagent in ethanol was studied in reduction of alkyl bromides, addition to olefin and alkylation onto heteroaromatic bases with alkyl bromides. The present organodisilane showed moderate to good reactivities for these three types of radical reactions.
- Yamazaki, Osamu,Togo, Hideo,Matsubayashi, Sou,Yokoyama, Masataka
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p. 1921 - 1924
(2007/10/03)
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- Novel Water-Soluble Organosilane Compounds as a Radical Reducing Agent in Aqueous Media
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The development of novel water-soluble organosilane compounds and their application to radical reactions in water medium have been studied. A series of novel organosilane compounds having hydrophilic groups, such as an ether group and a hydroxy group in the side chain to bear hydrophilicity, were synthesized by the reaction of trichlorosilane or tetrachlorosilane and Grignard reagents. The reactivities of these organosilane compounds were studied in the radical reduction of 2-bromoethyl phenyl ether in ethanol in the presence of triethylborane under aerobic conditions. The results showed that diarylsilane was the most effective among them. The radical reduction of alkyl and aryl halides with diarylsilane was applied to a reaction in aqueous media, which gave the corresponding reduction product in good yields. Thus, the present organosilanes are very useful for the reduction of water-soluble substrates, such as halo sugars in water.
- Yamazaki, Osamu,Togo, Hideo,Nogami, Genki,Yokoyama, Masataka
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p. 2519 - 2523
(2007/10/03)
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- Synthesis of novel 3'-C-(hydroxymethyl)thymidines and oligodeoxynucleotide analogues containing compressed 3'-C-hydroxymethyl-linked phosphodiester backbones
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Lombardo methylenation of the novel 2'-deoxy-3'-ketonucleosides 4 afforded 2',3'-dideoxy-3'-C-methylene nucleosides 5, which were subjected to catalytic dihydroxylation reactions. In the case of 5'-deoxynucleoside 5a, a 1:1 mixture of 3'-C-hydroxymethyl diastereoisomers 6a and 7a was obtained, whereas the 5'-O-silylated nucleoside 5b afforded 3'-C- (hydroxymethyl)thymidine derivative 6b as the only product. Sharpless asymmetric dihydroxylation of 5a proceeded in low yield to give 6a and 7a as a 10:3 mixture. 5'-O-Silylated nucleoside 6b was converted into the phosphoramidite synthon 9, which was applied in automated syntheses of oligodeoxynucleotides containing novel compressed 3'-C-hydroxymethyl linked phosphodiester backbones.
- Wengel,Svendsen,Jorgensen,Nielsen
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p. 1465 - 1479
(2007/10/02)
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- Facile Synthesis of 3'-O-Methylthymidine and 3'-Deoxythymidine and Related Deoxygenated Thymidine Derivative: A New Method for Selective Deoxygenation of Secondary Hydroxy Groups
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This paper deals with convenient synthesis of 3'-O-methylthymidine (2) and 3'-deoxythymidine (3), which involve Ag2O-promoted methylation and Barton-Robins reductive deoxygenation, respectively.New methods for the regioselective 3'- and 5'-deoxygenation of thymidine have also been developed.Namely, compound 3 was synthesized by the 3',5'-O-diacylation of thymidine with phenyl chlorothionoformate (PTCF) followed by the selective 3'-reduction with tributyltin hydride and successive alkaline hydrolysis. 5'-Deoxythymidine (18) was obtained by the 5'-selective acylation of thymidine with PTCF followed by reduction with tributyltin hydride.
- Sekine, Mitsuo,Nakanishi, Takeshi
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p. 924 - 928
(2007/10/02)
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