On the methanolysis of KBBL, an immunostimulant derived from ascorbic acid
作者:Erin Campbell、Bradley J Newhouse、Jon Bordner、Edward F Kleinman
DOI:10.1016/s0040-4020(01)87220-3
日期:1993.8
catalyst yielded the epimeric spiro ketals 4a and 4b along with a minor amount of the pyranoid ketal 2. Contrary to a literature report, treatment of KBBL in 2% methanolic HCl gave the rearranged methyl ester 3 rather than ketal 2. Ketals 2, 4a, and 4b are potentially useful intermediates for the further elaboration of the ascorbic acid nucleus of KBBL because the ketone and one hydroxyl of the butyrolactone
reaction L-ascorbic acid () undergoes addition to acrolein to give the tricyclic hemiacetal lactone . The constitution and relative configuration of was studied by a combination of NMR and IR spectroscopy. Ultimately, the structure of was determined by X-ray crystallography. The absolute stereochemistry follows from the known chirality of C-4 and C-5 of L-ascorbic acid. A mechanism for the reaction,