These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Photoinduced Regioselective Olefination of Arenes at Proximal and Distal Sites
preprintsubmitted on 26.11.2020, 15:29 and posted on 27.11.2020, 12:08 by Argha Saha, Srimanta Guin, Wajid Ali, Trisha Bhattacharya, Sheuli Sasmal, Nupur Goswami, Gaurav Prakash, Soumya Kumar Sinha, Hediyala B. Chandrashekar, S. S. Anjana, Debabrata Maiti
The Fujiwara-Moritani reaction has had a profound contribution in the emergence of contemporary C−H activation protocols. Despite the applicability of the traditional approach in different fields, the associated reactivity and regioselectivity issues had rendered it redundant. The revival of this exemplary reaction requires the development of a mechanistic paradigm that would have simultaneous control on both the reactivity and regioselectivity. Often high thermal energy required to promote olefination leads to multiple site functionalization. To this aim we established a photoredox catalytic system constituting a merger of palladium/organo-photocatalyst that forges oxidative olefination in an explicit regioselective fashion of diverse arenes and heteroarenes. Visible light plays a significant role in executing ‘regio-resolved’ Fuijiwara-Moritani reaction without the requirement of silver salts and thermal energy. The catalytic system is also amenable towards proximal and distal olefination aided by respective directing groups (DGs), which entails the versatility of the protocol in engaging the entire spectrum of C(sp2)−H olefination. Furthermore, streamlining the synthesis of natural products, chiral molecules, drugs and diversification through late-stage functionalization’s underscore the importance of this sustainable protocol. The photoinduced attainment of this regioselective transformation is mechanistically established through control reactions, kinetic studies and theoretical calculations.