Visible light induced the high-efficiency spirocyclization reaction of propynamide and thiophenols via recyclable catalyst Pd/ZrO2

A simple, highly efficient spirocyclization reaction without additional additives and oxidizing agents, and the photocatalyst Pd/ZrO2 can be recycled. It is a green environmentally friendly reaction pathway. [Display omitted] A new method for the synthesis of 3-thioazaspiro[4,5]trienones was developed using Pd nanoparticle catalysts, which are highly efficient, environmentally friendly and recyclable. Alkynes and thiophene phenols are effectively cyclized by Pd/ZrO2 catalyst under visible light irradiation. The present protocol simply utilizes visible light as the safe and ecofriendly energy source, and the Pd/ZrO2 nanocomposite as photocatalyst provides a simple and practical approach to various 3-thioazaspiro[4,5]trienones in moderate conditions to high yields