A versatile synthesis of enantiomerically pure cis- and trans-2,5-disubstituted morpholines is described. Hydroxynitrile lyase-mediated cyanide addition onto aldehydes provided cyanohydrins in virtually quantitative yield and excellent enantioselectivity. Subsequent formation of diastereomerically pure amino esters via a three-step, one-pot reduction-transimination-reduction sequence followed by reduction and simultaneous protection provided cyclization precursors. Finally, cyclization and SmI(2)-mediated reductive detosylation completed the synthesis of cis- and trans-2,5-disubstituted morpholines in good yields and excellent diastereoselectivities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.