Titanocene mediated reductive radical cyclization: an expeditious way to access pestalotiolactone A, myrotheciumone A, and scabrol A Sabnam Begum, Prof. Tushar Kanti Chakraborty Indian Institute of Science, India Radical-mediated C-C bond formation is an exemplary reaction often used as a key step in the total synthesis of many intricate and bioactive natural products because of its high efficiency and high functional group tolerance under neutral conditions. The free radical epoxide opening with concomitant cyclization reaction mediated by Cp 2 Ti(III)Cl has been extensively employed for the total synthesis of complex natural products and advance synthons. 1-3 To explore the versatility of this method, we have recently reported first stereoselective total syntheses of (+) pestalotiolactone A, (-) myrotheciumone A and (+) scabrol A using the Ti(III)-mediated reductive epoxide opening-cyclization protocol as a key step to assemble the bicyclic lactone core of these molecules with complete diastereoselectivity from D-malic acid based on chiral pool strategy. Finally, the deoxygenation and methylation delivered the target natural products. 4 References
1. Nugent, W. A.; RajanBabu, T. V. J.Am. Chem. Soc. 1988 , 110 , 8561. 2. Das, D.; Kant, R.; Chakraborty, T. K. Org. Lett . 2014 , 16 , 2618. 3. Singh, V.; Chakraborty, T. K. Chem. Asian J. 2021 , 16 , 753. 4. Begum, S.; Chakraborty, T. K. J. Org. Chem. 2021 , 86 , 11812.
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