Highly stereoselective total synthesis of octopyranose derivatives (original) (raw)

The recogmtton of the central role played by complex sugars m biologcally active products1 coupled with the synthetic value of related multlfunctlonal fragments2 has stimulated a great deal of interest m tlus matter 3 Recent reports from our laboratory+' ldentdied a novel strategy for the synthesis of higher carbon sugars based on stereoselective elonganon of homochlral Cn precursors using 2-(tnmethylnloxy)furan (TMSOF) In the event, BF3-medated ad&non selectively generates Cn+4 butenohdes which, by a senes of clean reactions, can be converted into advanced multifunctional structures or targets, by explcntmg the strong choral bias of the butenohde mamc?s TMSOF C,, Chuon C,,& Mamx Intermediate Target llus prmciple is apphed here in the total synthesis of an enanttomenc couple of octopyranoses, namely protected L-three-D-ralo-and D-three-L-talooctopymnose derivahves ~-6 and D-6 5 Four-carbon elongaaon of 1H. H-8b), 2 15, 2 14,2.11, 2 01 (four s, each 3H, OAc), 1 37, 1 36 (two s, each 3H, Me), l3C NMR (75 4