K. Bischofberger, A. Brink, O. G. D. Villiers
Jul 1, 1978
Citations
0
Influential Citations
6
Citations
Journal
Carbohydrate Research
Abstract
Abstract Addition of ethyl isocyanoacetate to 3- O -benzyl-1,2- O -isopropylidene-α- D - ribo -pentodialdo-1,4-furanose in ethanolic sodium cyanide gave two oxazolines that were hydrolysed during chromatography to two isomeric ethyl 3- O -benzyl-6-deoxy-6-formamido-1,2- O -isopropylidene-heptofuranuronates. Similarly, 1,2- O -isopropyl-idene-3- O -methyl-α- D - xylo -pentodialdo-1,4-furanose gave the 3- O -methyl-heptofuranuronates 7 and 11 . Reduction of 7 and 11 gave N -methylamino esters that exhibited Cotton effects from which the configurations at C-6 of 7 and 11 were deduced. The chiralities at C-5 of 7 and 11 were established by tetrahydropyranlation of 7 and 11 , followed by consecutive treatment with bis(2-methoxyethoxy)aluminium hydride, periodate, sodium borohydride, and dilute acid, to give 1,2- O -isopropylidene-3- O -methyl-α- D -glucofuranose and its β- L - ido epimer, respectively. Attempts to methylate HO-5 of 7 and 11 resulted in elimination. On formylaminomethylenation (ethyl isocyanoacetate and potassium hydride in tetrahydrofuran), 3- O -benzyl-1,2- O -isopropylidene-α- D - ribo -pentodialdo-1,4-furanose and its 3- O -methyl-α- D - xylo epimer each gave ( E )- and ( Z )-mixtures of alkenes that were hydrogenated to give mixtures of 5,6-dideoxy-6-formamido-heptofuranuronates.