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Glycals in Organic Synthesis: A Systematic Strategy for the Preparation of Uncommon Piperidine 1,2‐Dideoxy‐ L ‐azasugars and 2‐Deoxy‐1,5‐anhydro‐ L ‐hexitols
Author(s) -
Ciliberti Elena,
Galvani Roberta,
Gramazio Francesca,
Haddas Samantha,
Leonelli Francesca,
Passacantilli Pietro,
Piancatelli Giovanni
Publication year - 2007
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200600959
Subject(s) - chemistry , piperidine , glycosylation , glucal , glycosyl , stereochemistry , regioselectivity , glycal , organic chemistry , combinatorial chemistry , catalysis , stereoselectivity , biochemistry
A systematic synthetic strategy has been developed for producing uncommon piperidine 1,2‐dideoxy‐ L ‐azasugars. This method involves the formation of open intermediates such as 2 , 7 , and 10 easily by ring‐opening of D ‐glycals with aqueous mercury(II) acetate/sodium borohydride. A concise sequence of regioselective amination and cyclization reactions then allowed us to prepare the cyclic compounds 5a and 5b , L enantiomers of naturally occurring fagomine congeners such as 3‐ epi ‐fagomine ( II ) and 3,4‐di‐ epi ‐fagomine ( III ), from D ‐glucal and D ‐galactal, respectively. The unnatural 3,4‐di‐ epi ‐6‐deoxyfagomine 9 was obtained from L ‐rhamnal by the same reaction sequence. This straightforward chemistry has been shown to be useful for preparing glycosyl derivatives of 1,2‐dideoxy‐ L ‐azasugars starting from glycosyl glycals such as D ‐lactal, D ‐cellobial, D ‐maltal, and D ‐melibial, thus avoiding the usually lengthy glycosylation procedures. The flexibility of our protocol has been demonstrated by the easy conversion of the above‐described open intermediates into uncommon 2‐deoxy‐1,5‐anhydro‐ L ‐hexitols, never previously described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)