The approach of utilizing protecting groups (PGs) in organic chemistry has led to the successful syntheses of an array of useful organic compounds. This strategy has also addressed some of the complexities associated with many organic reactions. These PGs find useful applications in simple and complex reactions that involve the synthesis of large organic compounds such as peptides, oligosaccharides. The fundamental role of PGs is to prevent undesired reactions that could hinder the progress or completion of such reactions. It is important ideal PGs are utilized in this regard to achieve the desired objectives. This review describes the diverse protecting groups found in the literatures, the functional moieties for the protection, deprotection strategies, and their relevant applications in organic synthesis.

Background: Cancer cells restrain apoptotic and senescence pathways through Heat Shock Protein 70 (Hsp 70) at the intracellular level. These cells aid stimulus-independent growth and their higher metabolism rate requires Hsps. Hsps compensate abnormally increased substrate protein folding rate of cancer cells. Objective: Misfolding of substrate proteins specially signaling substrate proteins may not function properly therefore, Hsp70 folds these substrate proteins into their native-fully functional states, and this mode of action helps cancer cell survival. Method: Targeting Hsps is a promising cancer therapy and in this study 6,8,9-trisubstituted purine derivatives were designed and synthesized to inhibit Hsp70 and drive cancer cells to apoptosis. Further, oncogenic stimuli through inhibitors can induce an irreversible senescent state and senescence is a barrier to transformation. Results: Hsp70 helps cancer cells to bypass the cellular senescence program, however binding of N6-(4-isopropylaniline) analogue 7 depletes Hsp70 function as evidenced by aggregation assay and Hsp70 depletion induces senescence pathway. Conclusion: Taken together, the purine-based inhibitor-compound 7 effectively inhibit MCF-7 cell line. Moreover, the therapeutic potential with regard to the senescence-associated secretory phenotype has complementary action. Dual action of the inhibitor not only drives the cells to apoptosis but also force the cells to be in the senescence state and provides promising results specially for luminal A type breast cancer therapy.