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1,2‐Annulated Sugars: Synthesis of Polyhydroxylated 2,10‐Dioxadecalins with β‐ manno Configuration
Author(s) -
Borowski Daniel,
Zweiböhmer Tobias,
Ziegler Thomas
Publication year - 2016
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201601050
Subject(s) - alkene , chemistry , bicyclic molecule , diol , stereochemistry , metathesis , epoxide , stereoselectivity , absolute configuration , combinatorial chemistry , catalysis , organic chemistry , polymer , polymerization
A new synthetic route to 1,2‐pyran‐annulated O ‐glycosides (pyranopyrans) with β‐ manno configuration is presented. Starting from a benzyl‐protected allyl β‐2‐uloside obtained by C 2‐oxidation from the corresponding allyl glucoside, vinylation and ring‐closing metathesis provided a bicyclic alkene as a key substrate. Optimized reaction conditions involving the 2‐uloside were required to circumvent the formation of the unwanted 3,2‐enolone. Subsequent stereoselective alkene dihydroxylations were investigated and are presented. Diastereoselective catalytic osmoylation afforded the bicyclic β‐mannoside with syn ‐diol configuration. In contrast, a sequence featuring a directed vanadium‐catalyzed alkene epoxidation and epoxide opening provided the corresponding 2,10‐dioxadecalin target compound with trans ‐diol configuration. X‐ray crystallography was employed to study the molecular structure of the target compound with syn ‐diol configuration. In addition, the molecular packing and hydrogen‐bonding interactions of the hydroxy‐rich molecule were examined.