A Convenient Route to O-Glycosyl Lactates via Conjugate Addition to 2-Nitroglycals: Ring Closure to Novel Pyrano[2.3-b][1,4]-oxazines

Abstract

Lactate esters d-2a, l-2a, and d-2b could be readily added to 3,4,6-tri-O-benzyl-2-nitro-galactal (1) and 3,4,6-tri-O-benzyl-2-nitro-glucal (4), affording exclusively α- and β-anomers with galacto- and gluco-configuration, respectively. Nitro group reduction to the amino group and ester cleavage led to compounds 6a, 6b, and 7, which can be regarded as dipeptide mimetics. For these compounds the bicyclic pyrano[2.3-b][1,4]-oxazines 8-10 were prepared via ring closure.

glycal - nitroolefin - Michael additions - glycosides - peptide mimetic - bicyclic systems - azadioxadecalines

References

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Some related structures have been thus far reported as degradation products of natural compounds:

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<A NAME="RT05803SS-11">11</A>

This compound is commercially available.