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[摘要]：A modular methodol. for the synthesis of various 4-substituted-Ph C-2'-deoxyribonucleosides has been developed. Coupling of toluoylated halogenose with 4-bromophenylmagnesium bromide afforded the desired bis(toluoyl)-protected 1b-(4-bromophenyl)-1,2-dideoxyribofuranose (I), which was deprotected under Zemplen conditions to give the unprotected 1b-(4-bromophenyl)-1,2-dideoxyribofuranose, and reprotected to give the bis(tert-butyldimethylsilyl)-protected 1b-(4-bromophenyl)-1,2-dideoxyribofuranose (II). Alternatively, addn. of 1-lithio-4-bromobenzene on tert-butyldimethylsilyl-protected lactone, followed by redn. of the hemiketal, also gave bis(tert-butyldimethylsilyl)-protected bromophenyl nucleoside II. Intermediates I and II were then subjected to a series of palladium-catalyzed cross-coupling reactions, aminations, and C-H activation to give 1b-[4-(aryl-, alkyl-, or amino)phenyl]-1,2-dideoxyribofuranoses after deprotection. Finally, other types of 4-arylphenyl C-nucleosides were prepd. directly by aq.-phase Suzuki cross-coupling reactions of unprotected 3 with boronic acids under microwave irradn. |
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