Enantioselective Total Synthesis of Terreumols A and C from the Mushroom Tricholoma terreum |
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Authors: | M Sc Alex Frichert Prof Dr Peter G Jones Prof Dr Thomas Lindel |
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Institution: | 1. Institute of Organic Chemistry, Technical University Braunschweig, Braunschweig, Germany;2. Institute of Inorganic and Analytical Chemistry, Technical University Braunschweig, Braunschweig, Germany |
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Abstract: | The cytotoxic meroterpenoids terreumol A and C from the grey knight mushroom Tricholoma terreum were synthesized for the first time. The key step of the enantioselective total synthesis of terreumol C is a ring‐closing metathesis to form a trisubstituted Z double bond embedded in the 10‐membered ring of the 8.4.0] bicycle. Interestingly, the presence of a free hydroxy group in the metathesis precursor prevents cyclization and favors cross metathesis. (?)‐Terreumol C was converted into (?)‐terreumol A by diastereoselective epoxidation. Starting from 2‐bromo‐3,5‐dimethoxybenzaldehyde, 14 steps with an overall yield of 23 % are needed for the synthesis of (?)‐terreumol A. X‐ray analysis of the benzoquinone analogue of terreumol A provides independent proof of the absolute configuration. |
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Keywords: | medium-sized rings meroterpenoids natural products ring-closing metathesis total synthesis |
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