Photoinduced synthesis of functionalized spiro[2.3]hexane via an additive-free approach

A general green protocol for the synthesis of spiro[2.3]hexane avoiding the use of harmful and toxic reagents is described. Spirocyclic scaffolds can be constructed by using alkenes of low reactivity under visible-light irradiation only. Several synthetic advantages of this method are exhibited, including mild conditions, good functional-group tolerance, operational simplicity, and scalability. Mechanistic studies indicate that C–C bond formation occurs almost simultaneously with a light-sustained initiation process.