Recent developments in the Nazarov process

The Nazarov cyclisation is revisited. Recent improvements such as metal-catalysed Nazarov cyclisation, asymmetric Nazarov cyclisation, cationic cyclopentannelation of allenyl ethers, fluorine-directed Nazarov cyclisation, trapping of the photochemically generated oxyallyl zwitterions, and procedures called 'interrupted Nazarov reactions' have widely expanded the synthetic scopes of the process.