935263-70-0Relevant articles and documents
Cyclic 1,2-Diketones as core building blocks: A strategy for the total synthesis of (-)-terpestacin
Trost, Barry M.,Dong, Guangbin,Vance, Jennifer A.
supporting information; experimental part, p. 6265 - 6277 (2010/07/20)
We report a full account of our work towards the total synthesis of (-)-terpestacin (1), a sesterterpene originally isolated from fungal strain Arthrinium sp. FA1744. Its promising anti-HIV and anti-cancer activity, as well as its novel structure, make terpestacin an attractive synthetic target. A strategy based on the unique reactivity of cyclic 1,2-diketones (diosphenols) was developed and total synthesis of 1 was achieved in 20 steps, in the longest linear sequence, from commercially available 2-hydroxy-3-methyl-2-cyclopenten-1- one. The key feature of our synthesis is the double usage of a "Pd AAA-Claisen" protocol (AAA = asymmetric allylic alkylation), first in the early stages to generate the C1 quaternary center and then in the late stages to install the side chain. In addition, a rather unusual ene-1,2-dione moiety was synthesized and utilized as an excellent Michael acceptor to attach the C15 substituent. Several possible routes towards the total synthesis have been examined and carefully evaluated. During our exploration many interesting chemoselectivity issues have been addressed, such as a highly selective ring-closing metathesis and a challenging oxidation of a disubstituted olefin in the presence of three trisubstiuted ones.
A diosphenol-based strategy for the total synthesis of (-)-terpestacin
Trost, Barry M.,Dong, Guangbin,Vance, Jennifer A.
, p. 4540 - 4541 (2007/10/03)
A novel diosphenol-based strategy has been developed for the enantioselective synthesis of (-)-terpestacin by multiple usage of the α-diketone functionality, first in the "Pd AAA-Claisen rearrangement" protocol, and second by the employment of its oxidized form, the ene-1,2-dione, as an excellent Michael acceptor. This synthesis demonstrates that the sequence of O-allylation-Claisen rearrangement provides a chemo- and regioselective enolate allylation, which can be performed asymmetrically with respect to the enolate or allyl fragment or both. In addition, many interesting chemoselectivity issues, including a highly selective RCM and a dihydroxylation, have been addressed. Overall, this synthesis was accomplished in 20 longest linear steps (24 total steps) from the inexpensive and commercially available 3-methyl-1,2-cyclopentanedione. Copyright
