Synthesis of Oxepane Ring Containing Monocyclic, Conformationally Restricted Bicyclic and Spirocyclic Nucleosides from d-Glucose: A Cycloaddition Approach
journal contributionposted on 14.09.2007, 00:00 by Subhankar Tripathi, Biswajit G. Roy, Michael G. B. Drew, Basudeb Achari, Sukhendu B. Mandal
Carbohydrate-derived substrates having (i) C-5 nitrone and C-3-O-allyl, (ii) C-4 vinyl and a C-3-O-tethered nitrone, and (iii) C-5 nitrone and C-4-allyloxymethyl generated tetracyclic isoxazolidinooxepane/-pyran ring systems upon intramolecular nitrone cycloaddition reactions. Deprotection of the 1,2-acetonides of these derivatives followed by introduction of uracil base via Vorbrüggen reaction condition and cleavage of the isooxazolidine rings as well as of benzyl groups by transfer hydrogenolysis yielded an oxepane ring containing bicyclic and spirocyclic nucleosides. The corresponding oxepane based nucleoside analogues were prepared by cleavage of isoxazolidine and furanose rings, coupling of the generated amino functionalities with 5-amino-4,6-dichloropyrimidine, cyclization to purine rings, and finally aminolysis.
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isooxazolidine ringsfuranose ringspurine ringsoxepane ringnucleoside analoguescleavagebenzyl groupsintramolecular nitrone cycloaddition reactionsuracil baseVorbr üggen reaction conditionOxepane Ring Containing MonocyclicConformationally Restricted Bicyclictransfer hydrogenolysisSpirocyclic Nucleosidesspirocyclic nucleosides