Light-Dependent Amide or Thioamide Formation of Acylsilanes with Amines using Elemental Sulfur.

Due to the diverse chemical and physical properties of functional groups, mild and controllable ligation methods are often required to construct complex drugs and functional materials. To make diverse sets of products with tunable physicochemical properties, it is also useful to employ complimentary ligation methods that adopt the same starting materials. Here, we disclose the efficient and modular synthesis of amides or thioamides through the chemical ligation of acylsilanes with amines, simply by turning a light on or off.

Chiral Phosphoric Acid Catalyzed Enantioselective [4 + 2] Cycloaddition Reaction of α-Fluorostyrenes with Imines.

An enantioselective [4 + 2] cycloaddition reaction of α-fluorostyrenes with -benzoyl imines was demonstrated using a chiral phosphoric acid catalyst. Cycloaddition products having fluorine functionality were formed in high yields with excellent diastereo- and enantioselectivities. Further manipulation of the enantioenriched cycloaddition product with silyl enol ether in the presence of BiCl catalyst afforded substitution product with retention of the dihydro-4-1,3-oxazine framework through selective carbon-fluorine bond cleavage without loss of enantiomeric excess.

Chiral Phosphoric Acid-Catalyzed Enantioselective Phospha-Michael-Type Addition Reaction of Diarylphosphine Oxides with Alkenyl Benzimidazoles.

An enantioselective phospha-Michael-type addition reaction of diarylphosphine oxides with alkenyl benzimidazoles was demonstrated using a chiral phosphoric acid as the chiral Brønsted acid catalyst. Addition products having phosphorus and benzimidazole units were formed in high yields with excellent enantioselectivities in most cases. The reduction of the phosphine oxide unit in the addition product afforded the corresponding chiral phosphine, which is a potential benzimidazole-based chiral P,N-ligand, without loss of enantiomeric excess.