Two-step stereocontrolled synthesis of densely functionalized cyclic β-aminoesters containing four stereocenters, based on a new cerium(IV) ammonium nitrate catalyzed sequential three-component reaction

The cerium(IV) ammonium nitrate (CAN)-catalyzed sequential, one-pot reaction between alkylamines, beta-ketoesters, and chalcones afforded cis-4,6-disubstituted 2-alkylaminocyclohexene-1-carboxylic esters with complete diastereoselectivity. The carbon-carbon double bond of these compounds was reduced with sodium triacetoxyborohydride, again with complete diastereoselectivity. This novel two-step route allows the transformation of very simple acyclic starting materials into tetrasubstituted cyclohexane derivatives bearing four functional groups, including a cis-beta-aminoester moiety, and generates four stereocenters, three of which are adjacent and one of which is quaternary.