Abstract
The thesis consists of two parts: The first part is concerned with Diels-Alder reactions of masked o-benzoquinones (MOBs) 19 with [60]fullerene (1) and the second part describes the applications of MOBs in the synthesis of (±)-magellanine (52). The Diels-Alder reactions of various MOBs with [60]fullerene, affording novel and highly functionalized bicyclo[2.2.2]octenone-fused [60]fullerene derivatives 35 is discussed in the chapter 1. In the chapter 2, the total synthesis of (±)-magellanine (52) is presented. The linearly fused triquinane 152 was obtained by means of sequential intermolecular Diels-Alder reaction of an MOB generated in situ by DAIB mediated oxidation of acetovanillone (17d) in methanol followed by the photochemical oxa-di-p-methane rearrangement, selective protection of aceto functionality and the opening of a strained cyclopropane-ring. The transformation of triquinane 152 into compound 150 was achieved by functional group manipulations and 1,4-addition of a diallylcyanocuprate reagent. Tetracyclic compound 149 was obtained from compound 150 by selective reduction; protection and intramolecular cyclization. Finally, the total synthesis of (±)-magellanine (52) was accomplished by means of sequential regiospecific oxidative cleavage of cyclopentene ring of 149, double reductive amination followed by deprotection of TBS group. Thus, the total synthesis of (±)-magellanine (52) was achieved in 12.1% overall yield from commercially available acetovanillone (17d) in sixteen synthetic operations. Alternatively, the triquinane compound 170 was cyclized intramolecularly into tetracyclic 177. Subsequently, 177 was subjected to sequential regiospecific oxidative cleavage followed by double reductive amination to afford the targeted molecule (±)-magellanine (52), in 9.1% overall yield from commercially available acetovanillone (17d) in fourteen steps.