In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

Organic Photoredox Catalysis

N-Heterocyclic Carbenes in Late Transition Metal Catalysis

Asymmetric enamine catalysis.

Reactions that convert carbon–hydrogen (C–H) bonds into carbon–carbon (C–C) or carbon–heteroatom (C–Y) bonds are attractive tools for organic chemists, potentially expediting the synthesis of target molecules through new disconnections in retrosynthetic analysis. Despite extensive inorganic and organometallic study of the insertion of homogeneous metal species into unactivated C–H bonds, practical applications of this technology in organic chemistry are still rare. Only in the past decade have metal-catalyzed C–H functionalization reactions become more widely utilized in organic synthesis.Research in the area of homogeneous transition metal–catalyzed C–H functionalization can be broadly grouped into two subfields. They reflect different approaches and goals and thus have different challenges and opportunities. One approach involves reactions of completely unfunctionalized aromatic and aliphatic hydrocarbons, which we refer to as “first functionalization”. Here the substrates are nonpolar and hydrophobic a...

Weak coordination as a powerful means for developing broadly useful C-H functionalization reactions.

Small-molecule H-bond donors in asymmetric catalysis.

Comprehensive Asymmetric Catalysis I–III

Lewis and Bronsted acids can be utilized as more-effective tools for chemical reactions by sophisticated engineering ("designer acids"). The ultimate goal of such "designer acids" is to form a combination of acids with higher reactivity, selectivity, and versatility than the individual acid catalysts. One possible way to take advantage of such abilities may be to apply a "combined acids system" to the catalyst design. The concept of combined acids, which can be classified into Bronsted acid assisted Lewis acid (BLA), Lewis acid assisted Lewis acid (LLA), Lewis acid assisted Bronsted acid (LBA), and Bronsted acid assisted Bronsted acid (BBA), can be a particularly useful tool for the design of asymmetric catalysis, because combining such acids will bring out their inherent reactivity by associative interaction, and also provide more-organized structures that allow an effective asymmetric environment.

"Designer acids": combined acid catalysis for asymmetric synthesis.

Asymmetric Direct Aldol Reaction Assisted by Water and a Proline‐Derived Tetrazole Catalyst

Lewis acids in organic synthesis

A highly reactive and acidic chiral Bronsted acid catalyst, chiral N-triflyl phosphoramide, was developed. Highly enantioselective Diels-Alder reaction of alpha,beta-unsaturated ketone with silyloxydiene was demonstrated using this chiral Bronsted acid catalyst.

Hisashi Yamamoto

Papers

Comprehensive Asymmetric Catalysis I–III

"Designer acids": combined acid catalysis for asymmetric synthesis.

Asymmetric Direct Aldol Reaction Assisted by Water and a Proline‐Derived Tetrazole Catalyst

Lewis acids in organic synthesis

Design of chiral N-triflyl phosphoramide as a strong chiral Brønsted acid and its application to asymmetric Diels-Alder reaction.