Direct functionalizations of two distinct inert C−H bonds represent the most ideal ways to construct C−C bonds. Herein, we report an intermolecular vinylation of aldehydes using alkenes as the vinylating reagents through sequential two-fold C−H functionalizations. The merging of visible light and N-heterocyclic carbene catalysis allows for the coupling of alkenes with aldehydes through a dual catalysis relay enabled cross-dehydrogenative coupling mechanism. The use of diphenoquinone is essential for the success of this reaction, which plays an intriguing two-fold role in the reaction, as an electron acceptor as well as a radical reservoir for the radical coupling enabling the C−C forming process.

Phenols are ubiquitous substructures in natural products and bioactive compounds. However, practical methods for the direct construction of phenols under mild conditions remains challenging. Herein, a photocatalytic acceptorless dehydrogenative aromatization of cyclohexanones or cyclohexenones at room temperature has been developed. The reaction features the visible-light and cobalt co-catalyzed sequential dehydrogenation of in-situ formed enol silyl ethers, which are regarded as a challenging process. This operationally simple method enables a series of phenols with diverse substitution patterns from cyclohexanones or cyclohexenones, providing a general and straightforward method for the synthesis of phenols from simple starting materials under mild conditions.

Phenols are ubiquitous substructures in natural products and bioactive compounds. However, practical methods for the direct construction of phenols under mild conditions remains challenging. Herein, a photocatalytic acceptorless dehydrogenative aro-matization of cyclohexanones or cyclohexenones at room temperature has been developed. The reaction features the visible-light and cobalt co-catalyzed sequential dehydrogenation of in-situ formed enol silyl ethers, which are regarded as a challenging process. This operationally simple method enables the synthesis of a series of phenols with diverse substitution patterns from cyclohexanones or cyclohexenones. Moreover, diverse substituted 1,2-, 1,3-, and 1,4-benzenediols were obtained from cyclo-hexanediones, providing a general and straightforward method for the synthesis of phenols from simple starting materials un-der mild conditions

Comprehensive SummaryPhenols are ubiquitous substructures in natural products and bioactive compounds. However, practical methods for the direct construction of phenols under mild conditions remain challenging. Herein, a photocatalytic acceptorless hydrogen‐evolution aromatization of cyclohexanones or cyclohexenones at room temperature has been developed. The reaction features the visible‐light and cobalt co‐catalyzed sequential dehydrogenation of in‐situ formed enol silyl ethers, which are regarded as a challenging process. This operationally simple method enables the synthesis of a series of phenols with diverse substitution patterns from cyclohexanones or cyclohexenones. Moreover, diverse substituted 1,2‐, 1,3‐, and 1,4‐benzenediols were obtained from cyclohexanediones, providing a general and straightforward method for the synthesis of phenols from simple starting materials under mild conditions.