Research Projects

Recent advances in photoredox catalysis¹ have sparked considerable interest in radical-mediated coupling reactions, propelled by newly available catalysts and reagents. These innovations have enabled transformations previously considered unfeasible, leveraging mechanisms like photoinduced electron transfer (PET)² and hydrogen atom transfer (HAT)³. Modern methods, particularly photoredox-mediated Cross Dehydrogenative Coupling (CDC)⁴, offer streamlined pathways for material synthesis through efficient C–H functionalization⁵, promoting atom economy and environmental sustainability. This proposal aims to address the underexplored area of direct CDC for oxygen-containing heterocycles, specifically targeting dihydrofurans (DHF), dihropyrans (DHP) and their related analogs without prefunctionalization. Despite numerous impressive existing studies⁶ on substrates like tetrahydrofuran (THF), tetrahydropyran (THP), 1,4-dioxane, and 1,2-dimethoxyethane, the CDC protocols for these challenging DHP/or DHF systems remain limited due to the methylene groups uniquely located at distinct reactive sites (allylic vs α to O) and to date, to the best of our knowledge, there have been no reports on site-selective direct functionalization of these moieties containing α-oxoallyl C(sp3)-H groups under photoredox condition. The varied physicochemical properties of C(sp³)−H bonds, such as in cyclohexane, THF, DHP, THP, Toluene etc., reflect differences in their bond dissociation energies (BDEs). Thus, a reliable, selective method for site-selective functionalization is highly desirable for these types of moieties (DHP/DHF). The objective of this study is to develop a broadly useful α-oxyalkylation/arylation reaction that employs photoredox catalysis in conjunction with low-boiling easily available commercial feedstock ethers, a DHP/DHF frameworks, enabling precise functionalization to produce structurally diverse DHP/DHF derivatives and at the same time maintaining the olefin geometrical fidelity. Given the prevalence of these motifs in natural products, this approach is expected to not only expand synthetic strategies but also serve as a valuable tool for late-stage functionalization, fostering rapid molecular complexity in organic synthesis