Total synthesis of (−)-xanthatin

Enantioselective Synthesis of 8-<i>epi</i>-Xanthatin and Biological Evaluation of Xanthanolides and Their Derivatives

“…and divided into two groups according to the configuration of their cis-and trans-ring junctions. Representative examples of the cis-fused xanthanolides are the sundiversifolide (4), [7][8][9][10]11) the diversifolide (5) 10,12) and the 8-epi-xanthatin (9) 11,13,14) ; xanthatin (7) 11,15) and 11α,13-dihydroxanthatin (8) belong to the trans series. 11,16) They are known for their wide variety of interesting allelopathic, 17) cytotoxic, 18) anti-leishmanial, 19) and anti-MRSA activity.…”

“…A representative of the cis-fused γ-lactone series possessing a characteristic (E)-conjugated dienone functionality, this natural product was synthesized in 2005 by Martin et al, in the first reported 12) total synthesis of 1. In our previous synthesis of xanthatin (7), 15) which possesses a similar basic carbon framework and functionalities except for the stereochemistry on the ring junction, we employed two types of syn-elimination of selenoxides for the construction of the vinyl functionality at C1 (using the Nishizawa-Grieco protocol) and the exo-methylene at C11. In the present synthesis of 8-epi-xanthatin (9), out of ecological concerns, we decided not to use stoichiometric selenium reagents, as can be seen in our synthetic strategy in Chart 2.…”

Optimization of xanthatin extraction from Xanthium spinosum L. and its cytotoxic, anti-angiogenesis and antiviral properties

“…The first total synthesis of a xanthanolide, specifically (À)-dihydroxanthatin, was reported by Morken with sequential ruthenium-catalysed metathesis reactions [16]. Recently, Shishido and co-workers reported the enantiocontrolled total synthesis of (À)-xanthatin from an optically pure bicyclic lactone [17].…”

An Approach to the Bicyclic C‐5–C‐17/C‐19–C‐20 (BC) Portion of Neoclerodane Diterpenes by Intramolecular Diels–Alder Reaction

“…A straightforward solution for the latter transformation would be a one‐step Lewis acid mediated benzylic epimerization at some point along the synthetic pathway 9a,9b. Alternative routes involving Mitsunobu9c or oxidation–reduction inversion9d after ring opening might also be feasible. One obvious method for the attachment of the cis ‐fused A ring for 2 and 3 would involve temporary activation of (3 R ,4a S ,8a R )‐ 4 as a dienophile by allylic oxidation,10 and intermolecular Diels–Alder reaction with 3‐hydroxy‐2‐pyrone 11.…”