Photothermal cascade metathesis and cyclization

Cascade reactions are an attractive strategy in synthetic chemistry, as multiple bonds can be formed in one flask without the need for isolation or purification of any intermediate species. Classical synthesis of phenanthrenes requires highly oxidative or strongly acidic conditions, diluted concentrations (∼10−4 M), or complex transition-metal catalysts. As the first photothermal cascade reaction of aromatic ketones and gem-difluoroalkenes, carbonyl-olefin metathesis and dehydrogenative cyclization occurs successfully in one pot, affording various phenanthrenes under mild conditions.