I. Catalytic Enantioselective Synthesis of 2-Aryl Chromenes II. Total Syntheses of Alstonine and Serpentine via Cooperative Catalysis III. Progress Towards Enantioselective Oxa-Pictet-Spengler Cyclization via Phosphoric Acids

An enantioselective Pd-catalyzed 6-endo-trig reaction to generate 2-aryl chromenes is presented in the first chapter. A novel monodentate phosphoramidite ligand -- identified through a systematic optimization of a TADDOL-derived ligand set -- enanbled the synthesis of a wide range of 2-aryl-2H-chromenes with high yield and enantioselectivity under mild conditions. To illustrate the utility of this new methodology, the products obtained from this reaction were transformed into two bioactive flavonoids (namely, catechin and hydroxyflavanone) through functionalization of the benzopyran olefin. The syntheses of alstonine and serpentine, two potential neurotherapeutics, are disclosed in chapter two. The key step involves a cooperative hydrogen bonding/enamine-catalyzed Michael addition. In the last chapter, efforts toward the enantioselective oxa-Pictet-Spengler cyclization to oxazinoindole using BINOL- and SPINOL-derived chiral phosphoric acids are described.