ヌクレオシドおよびヘキソピラノシドの位置選択的炭素鎖延長反応

抄録

Regioselective carbon-chain extension at 5'-position of nucleosides and 2-or 3-position of methyl 4, 6-Ο-benzylidene-D-hexopyranosides are described.
Ο²-Methyluridine, N³-methyluridine, 4-triazoyl-1- (β-D-ribofuranosyl) -2 (1H) -pyrimidinone, and N¹, N⁶, 2', 3'-Ο-tetrabenzoyladenosine reacted with 2, 6-di-t-butyl-4-nitrophenol, diethyl azodicarboxylate, and triphenylphosphine to give the corresponding 4- (nucleoside-5'-aci-nitro) -2, 6-di-t-butylcyclohexa-2, 5-dienones (aci-nitroester of nucleosides) without any detectable formation of products derived from the reaction at the 2'-and/or 3'-hydroxyl groups. The reaction of aci-nitroesters with stabilized Wittig reagents afforded carbon-chain extended nucleosides having 5'-6'-double bond. When the sequence of the reactions was carried out in one-pot procedure, the yields of 5-eno-furanosyl-pyrimidines and-purines were markedly increased.
Methyl 2, 3-anhydro-4, 6-Ο-benzylidene-α-D-allopyranoside and-gulopyranoside reacted with allylic Grignard reagents giving the corresponding 2-deoxy-2-propenyl-α-D-hexopyranosides, while methyl 2, 3-anhydro-4, 6-Ο-benzylidene-α-D-mannopyranoside afforded 3-deoxy-3-propenyl-altropyranosides. The regioselectivity could be explained by diaxial opening of fixed epoxide ring. The reaction of 4, 6-Ο-benzylidene-1, 2-dideoxy-3-Ο-mesyl-D-ribo-hex-1-enopyranose and-xylo-hex-1-enopyranose with alkylmagnesium halides resulted in the formation of 1-C-and/or 3-C-substituted enopyranoses. On the other hand, allylic Grignard reagents selectively attack the 1-position of the 3-Ο-mesyl-glycals from β-side to afford 1-C-prop-2-enyl-β-D-hex-2-enitols.