Efficient, stereoselective synthesis of oxazolo[3,2-a]pyrazin-5-ones: novel bicyclic lactam scaffolds from the bicyclocondensation of 3-aza-1,5-ketoacids and amino alcohols.

Josef R Bencsik, Timothy Kercher, Michael O'Sullivan, John A Josey

Index: Org. Lett. 5(15) , 2727-30, (2003)

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Abstract

[reaction: see text] The bicyclocondensation of 3-aza-1,5-ketoacids and amino alcohols furnished novel oxazolo[3,2-a]pyrazin-5-one scaffolds possessing angular, ring junction substituents in high yield with excellent levels of substrate-based diastereocontrol. Mild oxidation of serinol-derived scaffolds provided access to a new class of constrained dipeptide surrogates. Deprotection of the endocyclic amine contained within these scaffolds allows for further diversification via N-functionalization.