Enantioselective synthesis of tetracyclic quassinoid intermediates via a diene transmissive diels-alder strategy
Date
1994
Authors
Tu, Noah Pui-Wai
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Abstract
Starting from 2-cyclohexene-1-one 62, an enantioselective synthetic route to an optically pure tetracyclic quassinoids intermediate, compound 102, was developed. Two bulky substituents (methyl at C₄ and t-butyldimethylsilyloxy at C₃) were introduced to affect the mode of the intramolecular Diels-Alder cycloaddition to the desired face which consequently controlled the absolute stereochemistry at C₅, C₆, C₇ and C₁₀ of the tetracyclic compounds. This strategy, based on a diene-transmissive Diels-Alder cycloaddition, could be used for the enantioselective total synthesis of quassinoid bearing the same skeleton and stereochemistry at the ring junctions.
In addition, the added functionalities of the methyl at C₄ and t-butyldimethyl-silyloxy at C₃ set ring A in place for the totally synthesis of Bruceantin.