Synthesis of pseudo-sugar derivatives from 5exo, 6exo-dihydroxy-endo- and -exo-7-oxabicyclo[2.2.1]heptane-2-carboxylic acids

Synthesis and Conformational and Biological Aspects of Carbasugars

“…When acid 576 was treated with hydrogen peroxide and formic acid, the hydroxylactone 577 was formed. This compound has been the key intermediate in the syntheses of β- dl -gluco-, α- dl -galacto-, β- dl -allo-, and α- dl -gulocarbapyranoses and the carbasugar analogues of KDO and NANA . The majority of the remaining carbapyranoses, α- dl -manno- 261 , β- dl -manno- 261 , β- dl -altro- 261 , α- dl -ido- 261 α- dl -gluco- 262 , and α- dl -allopyranose, were derived from lactone 578 , also prepared from 576 by the action of hydrobromous acid (Scheme ).…”

Novel conversions of a multifunctional, bio-sourced lactone carboxylic acid

“…Predictably, epoxidation using peracetic acid led to efficient formation of the exo-epoxide 11 . We initially used in situ generated performic acid at 60 °C 19 to effect this epoxidation, but on one occasion we observed a strong exotherm. We do not recommend use of this unstable reagent 20 if alternative expoxidation reagents will suffice.…”

Synthesis of a Carbasugar Analogue of a Putative Intermediate in the UDP-Galp-Mutase Catalyzed Isomerization

“…The 7-oxabicyclo[2.2.1]heptane skeleton was accessible via a Diels−Alder reaction of excess furan and methyl acrylate in the presence of zinc iodide at 40 °C 8a. After 3 days, this gave 15% of the desired exo- isomer as the predominate product (2:1 exo : endo ).…”

“…Separation of this diastereoisomer from the endo -form was achieved using SiO 2 flash chromatography, albeit with some decomposition on the column. A sufficient quantity of the exo -isomer was generated for epoxidation with m -CPBA to give methyl (±)-3,8-dioxatricyclo[3.2.1.02,4]octane-6-carboxylate 8b. However, despite investigating both nucleophiles (i.e., KOH in DMSO/H 2 O) and protic acids (i.e., HClO 4 in hexafluoro-2-propanol), it was not possible to selectively open the epoxide without decomposition of the oxanorbornane system.…”