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1,2‐ cis ‐ C ‐glycoside synthesis by samarium diiodide‐promoted radical cyclizations
Author(s) -
Skrydstrup Troels,
Mazéas Daniel,
Elmouchir Mohamed,
Doisneau Gilles,
Riche Claude,
Chiaroni Angèle,
Beau JeanMarie
Publication year - 1997
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19970030822
Subject(s) - hexamethylphosphoramide , chemistry , samarium diiodide , glycosyl , anomer , radical cyclization , yield (engineering) , samarium , glycoside , ring (chemistry) , medicinal chemistry , stereochemistry , organic chemistry , materials science , metallurgy
The samarium diiodide reduction of glycosyl pyridyl sulfones bearing a silicon‐tethered unsaturated group at the C2–OH position leads to the stereo‐specific synthesis of 1,2‐ cis‐C ‐glycosides in good yield after desilylation. These reactions proceed via an anomeric radical with subsequent 5‐ exo cyclization. Unlike the corresponding glycosyl phenyl sulfones, the pyridyl derivatives react instantaneously with samarium diiodide and do not require a cosolvent such as hexamethylphosphoramide (HMPA). Under these reaction conditions radical cyclization precedes the second reduction step. Examples of 5‐ exo‐trig and ‐ dig ring closures are given. The synthetic utility of this method was demonstrated by a short synthesis of methyl C ‐isomaltoside.