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

作者：Ciliberti Elena^*; Galvani Roberta; Gramazio Francesca; Haddas Samantha; Leonelli Francesca; Passacantilli Pietro; Piancatelli Giovanni

来源：European Journal of Organic Chemistry, 2007, (9): 1463-1473.

DOI：10.1002/ejoc.200600959

• glycals
• azasugars
• fagomine
• glycosides
• glycopyranosyl derivatives
• hexitols

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 animation 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.

• 出版日期2007-3