Radical transformations have emerged as a powerful tool for the synthesis of valuable chemical products; however, prevailing strategies heavily relied on the use of precious transition-metal catalysts such as iridium, ruthenium or silver, impeding their general applications. The motivation of this work was to develop new catalytic systems using cheap and sustainable Earth-abundant element metals that allow efficient synthesis of otherwise challenging molecules via radical mechanisms. Chapter 1 describes the development of two general ring-opening fluorination protocols to access valuable fluoroketones. Apart from previous strategies using high loadings (20 – 50%) of precious silver metals, ceric ammonium nitrate (CAN) was found to be able to mediate the efficient synthesis of γ-fluoroketones from cyclobutanols in open flask conditions within 30 minutes. Despite these advantages, the reaction is not catalytic as Selectfluor® is unable to re-oxidize the reduced cerium species in the catalytic cycle due to its lower oxidation potential (-0.04V vs SCE) than CAN (+1.02V vs SCE). Further, the reaction produces γ-fluoroketones in moderate yields (41 – 69%) accompanied by the formation of homocoupling side-products and possesses limited applicability to cyclopropanol substrates. In light of these limitations, we investigated different transition metals and found that 10 mol% Mn(OAc)2·4H2O can produce moderate to high yields (up to 91%) of β- and γ-fluoroketones at 45 – 60 °C from cyclopropanols and cyclobutanols, respectively. Together, these two advanced strategies have successfully incorporated cheap and Earth-abundant metals to the ring-opening fluorination of strained alcohols in a stoichiometric or catalytic fashion without using precious metals. Chapter 2 outlines the study of iron-catalyzed decarboxylative protonation reaction using thiol as the HAT co-catalyst. This reaction has addressed several issues encountered in previous approaches, including the requirement to preactivate carboxylic acid and the use of superstoichiometric hydrogen atom donor and/or precious metal catalysts. Toward examining the scope, the reaction was found to be able to tolerate a variety of functional groups and compatible with complex molecules and natural products with great scalability using a regular round bottom flask set-up. Notably, this protocol exhibits superior chemoselectivity towards carboxylic acid compared to Fukuzumi-type photocatalysts and can readily incorporate deuterium using deuterium oxide to afford great isotope incorporation efficiency and yields. To further capitalize on this work, this dual catalytic system was adapted for the hydrofluoroalkylation of alkenes and found to be able to replace the use of expensive electrophilic fluoroalkylating agents, stoichiometric oxidants/reductants and hydrogen atom donors with simple fluoroacetic acid and water to make diverse fluorinated molecules. Chapter 3 describes a new C–H azidation protocol using 1 mol% of decatungstate photo-catalyst and commercial acetamidobenzenesulfonyl azide (p-ABSA) as the azide source. Different from the previous photo-catalytic methods using precious ruthenium or acridinium photoredox to indirectly activate C–H bond, the reaction processes via a direct hydrogen atom transfer mechanism to afford moderate to good yields of products and excellent turnover numbers. Overall, these new radical strategies have shown great advances and improved sustainability compared to the previous works using noble and expensive transition metals and harsh conditions. In addition to study the unprecedent catalytic properties of Earth- abundant elements, a wide variety of valuable fluorinated and azido molecules were synthesized and characterized for their potential applications.