Catalytic Regio- and Stereoselective Alkene Sulfenoamination for 1,4-Benzothiazine Synthesis
An alkene sulfenoamination reaction with 2-aminothiophenol is developed using iodide catalysis. This reaction renders access to useful 1,4-benzothiazines with good functional group compatibility including both electron-donating and electron-withdrawing substituents. The reaction is proposed to proceed through an inversion of the polarity of the thiol functionality. Our mechanistic studies reveal that both thiiranium and thiyl radical pathways are plausible and that the disulfide reagent can also function as a viable substrate in this reaction.
Organocatalytic Approach for Transfer Hydrogenation of Quinolines, Benzoxazines and Benzothiazines
Abstract: This study reports on the thiourea dioxide catalyzed transfer hydrogenation of diverse C=N–containing heterocyclic compounds with Hantzsch ester as the hydrogen source. With this cost effective and readily available catalyst, a wide range of 2-s
Chiral phosphoric acid catalyzed oxidative kinetic resolution of cyclic secondary amine derivatives including tetrahydroquinolines by hydrogen transfer to imines
A chiral Bronsted acid catalyzed dehydrogenative kinetic resolution of tetrahydroquinoline derivatives, which are representative of cyclic secondary amines, based on their hydrogen transfer to aromatic imines was efficiently achieved with high enantioselectivities. This hydrogen transfer of tetrahydroquinolines to imines was not driven by their aromatization to quinolines. This dehydrogenative kinetic resolution could be also applied to the asymmetric synthesis of various benzofused heterocycles containing secondary amine cores.