A practical approach to regioselective O-benzylation of primary positions of polyols
摘要:
Exposure of saccharide polyols to a moderate excess of benzyl bromide and DIPEA at 90 degrees C results in the regioselective O-benzylation of primary positions in moderate to good yields. The reactions can be performed without inert atmosphere and provide synthetically useful yields within a few hours. (c) 2013 Elsevier Ltd. All rights reserved.
A de novo synthesis of pentoses is described starting from (Z)-2-buten-1,4-diol (1). The key step is the enzyme catalysed enantioselective HCN-addition to O-protected 4-hydroxybut-2-enal using the hydroxynitrilelyase from Hevea brasiliensis, followed by an asymmetric dihydroxylation. For the cyanohydrin reaction the influence of the configuration of the double bond and of the protecting group was