**Author details**

the α-position is ready for reactivity. Photosensitizer tetraphenylporphyrin (TPP)

substrate enamine through an ene-type reaction, forming α-hydroperoxide which is then reduced using NaBH4 to get 1,2-diols. Later this methodology was extended to

The α-functionalization of carbonyl compounds is easily carried out, whereas functionalizing at the β-position is not easy and requires multiple synthetic operations. With creativity and with clear understanding of radical chemistry using a VLPC protocol, these authors have enolized the cyclic ketones; thereby a double bond is formed, and the radical chemistry created an allyl radical at the β-position. In the reaction medium, the iridium-based catalyst generated arene radical cation from cyanoarenes, which reacts with the allyl radical and forms the β-substituted ketones with the elimination of the cyanide group from the arene (**Figure 29**).

A relay visible-light photocatalysis strategy using formal 4+1 annulation and aromatization was achieved. Three successive photoredox cycles (one oxidative cycle and two reductive quenching cycles) were engaged in a reaction with one photocatalyst. Multiple quenching cycles could be demonstrated in a single reaction involving formal 4+1 annulation of hydrazone with 2-bromo diethylmalonate [23]

Photosynthesis has attracted biologists, physicists, and chemists for centuries; chemists by understanding how the plants synthesized chemicals using sunlight have been inspired, and that resulted in this new domain. Ultimately these new sets

cyclic ketones and yielded appreciable enantioselectivity (**Figure 28**).

*Photophysics, Photochemical and Substitution Reactions - Recent Advances*

**22. Enamine catalysis: β-arylation of ketones**

**23. Relay visible-light photocatalysis**

(**Figure 30**).

**Figure 29.** *Ketone β-arylation.*

**24. Conclusion**

**Figure 30.** *Relay VLPC.*

**150**

O2 by the action of visible light, which then reacts with the

sensitizes <sup>3</sup>

O2 to <sup>1</sup>

Alwar Ramani<sup>1</sup> , Shobha Waghmode<sup>2</sup> and Suresh Iyer<sup>3</sup> \*


\*Address all correspondence to: s.iyer@ncl.res.in

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
