Abstract
This thesis focuses on the hetero-Diels-Alder reactions of masked o-benzoquinones (MOBs) and the reactivity of MOBs in the presence of Lewis acids. The research of this thesis consists of three main chapters: chapter one describes the hetero-Diels-Alder reactions of MOBs with chiral nitroso compounds. Chapter two is the synthesis of the natural product conduramine A-1. Finally, chapter three deals with the 1,3-methoxy rearrangement of MOBs catalyzed by Lewis acids.We utilized nitroso compounds bearing chiral menthol skeleton as a dienophile to examine hetero-Diels-Alder reactions of MOBs. We expected that the naphthalene substitution on the menthol moiety could enhance the shielding effect during the hetero-Diels-Alder process and improve diastereoselectivity. When the MOB is I-21a, the diastereomeric excess of hetero-Diels-Alder reaction is up to 95%.We then applied the hetero-Diels-Alder reaction of MOBs to the total synthesis of the natural product conduramine A-1. We employed phenol II-57 bearing the MOM protecting group as a starting material. After hetero-Diels-Alder reaction, selective reduction, hydrolysis and N-O bond cleavage, II-64 was obtained. The natural product conduramine A-1 can then be easily obtained by removing Cbz group of II-64.Finally, we also found that p-quinol ethers can be generated via 1,3-methoxy rearrangement of MOBs catalyzed by Lewis acid. Based on the mechanistic study, we knew that 1,3-methoxy rearrangement of MOBs is a reversible process and the key intermediate is carbocationic species. At last, p-quinol ethers can also be generated from simple phenols by one-pot strategy.