Synthesis of Anomeric Spiro Uracil Nucleosides with an Orthoester Structure: Stereoselective Cyclization Controlled by the C6-Substituent
摘要:
Uracil nucleosides having an anomeric orthoester structure were synthesized fi om 2'-deoxy-6-(hydroxyalkyl)uridines through hypoiodite-initiated cyclization. The hydroxyalkyl substituent at the 6-position was found to control the anomeric stereochemistry (beta/alpha=7/1 similar to 1/46) of the cyclization. The transition state geometry of the reaction was postulated based on the X-ray crystallographic structure of the cyclized product 7 alpha to elucidate the observed stereoselectivity. (C) 1997 Elsevier Science Ltd.
A 1,5-hydrogen migration of a conveniently situated alkoxyl radical affords spironucleosides which possess an unusual orthoamide structure at the anomeric position; X-ray crystallography establishes the configuration of the C-1′ position.
Synthesis of 6-substituted2'-deoxyuridines can be effected by lithiation of 3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)-2'-deoxyuridine with LDA followed by the reaction of its lithio derivative with electrophiles. This method provides a general, regiospecific and simple route to various types of 6-substituted2'-deoxyuridines which have, so far, been known to be difficult to prepare.
作者:Yahaira Reyes、Alexander Mebel、Stanislaw F. Wnuk
DOI:10.1080/15257770.2023.2271023
日期:2024.5.3
Azido nucleosides have been utilized for click reactions, metabolic incorporation into cellular DNA, and fluorescent imaging of live cells. Two classes of 6-azido modified uracil nucleosides; one w...
叠氮核苷已用于点击反应、代谢掺入细胞 DNA 以及活细胞的荧光成像。两类6-叠氮基修饰的尿嘧啶核苷;一瓦...