Photocatalytic initiation of thiol-ene reactions: synthesis of thiomorpholin-3-ones

A mild, redox neutral photocatalytic method for alkene hydrothiolation is reported. Utilizing visible-light activation, catalytic radical initiation is achieved with the transition metal complex Ru(bpy)3Cl2, enabling rapid access to a diverse set of thiol-ene coupled products in excellent yield. On the basis of a strong observed background reaction in some cases, we have developed a solvent-free, Lewis acid-promoted tandem amidation-hydrothiolation sequence, providing thiomorpholin-3-ones in a one-pot operation from commercially available materials.