| Microwave-assisted organic synthesis (MAOS) is recognized as a highly efficient synthetic technology for preparation of organic compounds (compound libraries) in recent years, and it has been used in many fields of chemistry and interdisciplinary research including pharmaceutical industry. For drug discovery research, access to a variety of heterocycle-containing molecules is crucial. This thesis focuses on design and synthesis of a novel class of tetracyclic scaffold by fusion of phenanthridine with morpholine ring systems. The key reaction is an annulation via Pd-catalyzed C-H activation under controlled microwave heating, providing 2,3-dihydro-3-oxo-5H-[1,4]oxazino[2,3,4-mn]phenanthridine derivatives in excellent yields.The first chapter gives a brief introduction to microwave chemistry followed by selected synthesis of 3,4-dihydro-3-oxo-2H-1,4-benzoxazines from 2-aminophenols and 2-nitrophenols, and recent progress in C-H activation and its application in natural product synthesis.Chapter 2 is the main part of the thesis, describing the results of the three-step synthesis of the tetracyclic scaffold. Starting from 2-aminophenols, reductive N-alkylation with 2-bromobenzaldehyde afforded N-(2-bromobenzyl)-2-amino-phenols. The latter underwent a one-pot annulation with 2-bromo alkanoates under microwave irradiation to furnish N-(2-bromobenzyl)-3,4-dihydro-3-oxo-2H-1,4-benzoxazines. Finally, in the presence of Pd(OAc)2-dppf, and K2CO3, N-(2-bromobenzyl)-3,4-dihydro-3-oxo-2H-1,4-benzoxazines was subjected to C-H activation annulation at 150℃in PhMe with controlled microwave heating to form the desired products. Selected compounds with substituents at C2 and C10-12 have been synthesized in excellent yeilds.Experimental details, compound characterization, and cited references are found at the end of thesis. Overall, this thesis work provides a three-step synthesis of a novel N,O-containing tetracyclic scaffold, which may be useful for pharmaceutical research.
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