DIRECT PREPARATION OF 1,2 3,5-DI-O-CYCLOHEXYLIDENE-ALPHA-D-XYLOFURANOSE FROM CORNCOBS AND ITS CONVERSION TO 1-O-ACETYL-2,3,5-TRI-O-BENZOYL-D-RIBOFURANOSE/
M. Popsavin et al., DIRECT PREPARATION OF 1,2 3,5-DI-O-CYCLOHEXYLIDENE-ALPHA-D-XYLOFURANOSE FROM CORNCOBS AND ITS CONVERSION TO 1-O-ACETYL-2,3,5-TRI-O-BENZOYL-D-RIBOFURANOSE/, Collection of Czechoslovak Chemical Communications, 59(8), 1994, pp. 1884-1888
A novel synthesis of 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose (I)
has been described starting from 1,2:3,5-di-O-cyclohexylidene-alpha-D
-xylofuranose (II), obtained directly from the crude xylose syrup orig
inated from corncobs. Partial acid hydrolysis of II gave 1,2-O-cyclohe
xylidene-alpha-D-xylofuranose (III). Selective benzoylation of primary
C-5 hydroxyl group of III followed by tosylation of C-3 hydroxyl grou
p afforded IV in an overall yield of 67%. Mild acid methanolysis of IV
gave the corresponding methyl xylofuranosides V which were further be
nzoylated to afford 2,5-di-O-benzoyl derivatives VI in 65% yield. Solv
olysis of VI in 95% DMF gave a mixture of 2,5- and 3,5-di-O-benzoylrib
ofuranosides VII, which were subsequently converted into the correspon
ding tribenzoates VIII. An acetolysis of VII afforded I in an overall
yield of 96% related to VI.