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Isomérisations en chimie des sucres. II Fermetures de cycles par attaque nucléophile intramoléculaire sur des carbones sp 2 à caractère électrophile: Furannoses hybridés sp 2 en C3
Author(s) -
Tronchet J. M. J.,
Bourgeois J. M.
Publication year - 1971
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19710540609
Subject(s) - chemistry , yield (engineering) , intramolecular force , acetone , hydrolysis , medicinal chemistry , stereochemistry , electrophile , catalysis , organic chemistry , materials science , metallurgy
When heated with one equivalent of H 2 O, the 1,2: 5,6‐di‐O‐isopropylidene‐α‐D‐ ribo ‐ and ‐ xylo ‐hexofuranos‐3‐uloses loose one molecule of acetone and yield the 3, 6‐anhydro‐1, 2‐O‐isopropylidene‐α‐D‐ ribo ‐ and ‐ xylo ‐hexofuranos‐3‐ulose ketohydrols. The carbonyl group of the starting material seems to provide some kind of intramolecular electrophilic assistance to the hydrolysis of the 5, 6‐O‐isopropylidene group. When the oxygen of the carbonyl group is replaced by cyanomethylene, an analogous cyclisation takes place under base catalysis, provided that C6 bears a free hydroxyl group.