Chiral Spirophosphoric-Acid-Catalyzed Divergent Vinylogous Mannich and -Friedel-Crafts Reactions of 2-Methoxyfuran.

The first enantioselective vinylogous Mannich reaction is developed using 2-methoxyfuran under chiral spirophosphoric acid catalysis. The strategy involves 4-isoxazoline derivatives as cyclic ketimine surrogates and provides γ-butenolide scaffolds (up to 97% ee and >20:1 dr). The mechanistic investigations suggest that an generated water molecule plays a crucial role in delivering γ-butenolide, while the use of molecular sieves delivers -Friedel-Crafts products.

Synthetic Transformations Using Molecular Oxygen-Doped Carbon Materials.

Carbon materials like activated carbon (AC) undergo chemisorption with O to give species with electron deficiency in the carbon skeleton and negative charge at the oxygen end that upon reaction with PPh and benzoic acid afford PhP═O. Whereas amine donors react with O-chemisorbed AC and nucleophiles to give dehydrogenatively coupled products in 67-89% yields via the corresponding radical cation and iminium ion intermediates, the reactions using β-naphthoxide derivatives give the corresponding oxidatively coupled bi-2-naphthol products in 68-95% yields.