PHOTOCHEMISTRY - using light for C - C bond forming reactions

In 1912 Ciamician (the recognized father of photochemistry) wrote: ‘On the arid lands there will spring up industrial colonies without smoke and without smokestacks; forests of glass tubes will extend... everywhere; inside of these will take place the photochemical processes'. Yet, to date Science has not been able to fulfill this dream.

Fortunately, organic chemists have recently started to realize the potential of light driven reactions. In such processes, absorption of a photon leads to electronically excited states of a reagent and in fact, by definition the reaction starts from a high energy level contrary to thermal reactions. This characteristic, "facilitate a thermally unachievable, energetically uphill reaction" (Noyori).

Over the last few years, chemical photocatalysis has been a rapidly growing field and the development of new and green activation modes in selective but particularly enantioselective synthesis under visible light irradiation has become a fundamental objective for organic chemists. Recently, strategies have been developed in which efficient catalytic processes that work under stereochemical control giving chiral molecules in an asymmetric fashion can be carried out by two catalysts working concomitantly for a single chemical transformation. With respect to single catalysts, to date, chiral photoredox catalysts are represented by only two examples of chiral Ru- and Ir-complexes but a general solution for stereoselective, visible-light induced photoredox chemistry with single molecule catalysts represents a long standing challenge and is highly desirable.

To this end our group focuses on the development of a new approach towards purely organic, enantioselective photoredox catalysis for the formation of C-C bonds which are of great significance in organic synthesis. In particular, it is specifically planned to concentrate on chiral organic dyes that absorb visible light in order to take one step forward and eliminate the use of toxic and expensive Ru- and Ir-complexes that are only effective for certain substrates.