C4'-spiroalkylated nucleosides having sulfur incorporated at the apex position.
Methodology based on the concept of thionium ion-initiated pinacolic ring expansion has been developed for accessing C4'-spirocyclic thionucleosides. The readily available racemic ketones 6 and 37 are conveniently resolved via their acetals with (R)-mandelic acid. Subsequent reactions beginning with utilization of the Pummerer rearrangement lend themselves to functionalization of the spirocyclic core and ultimately incorporation of the nucleosidic bases. Limitations to this strategy are pointed out. Acquisition of the alpha- and beta-isomers at C4' is equally facile. Absolute configurational assignments have been made possible by X-ray crystallography.
Paquette
Leo A
LA
Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210, USA. paquette.1@osu.edu
Fabris
Fabrizio
F
Gallou
Fabrice
F
Dong
Shuzhi
S
D000080:Acetals / Q000737:chemistry; D000478:Alkylation; D003181:Complement C4 / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007536:Isomerism; D007659:Ketones / Q000737:chemistry; D008333:Mandelic Acids / Q000737:chemistry; D009705:Nucleosides / Q000138:chemical synthesis*; D013141:Spiro Compounds / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*; D013872:Thionucleosides / Q000138:chemical synthesis* / Q000737:chemistry
D000080:Acetals; D003181:Complement C4; D007659:Ketones; D008333:Mandelic Acids; D009705:Nucleosides; D013141:Spiro Compounds; D013872:Thionucleosides; D013455:Sulfur; C037938:mandelic acid