A concise total synthesis of (+)-propindilactone G, a nortriterpenoid isolated from the stems of Schisandra propinqua var. propinqua, has been achieved for the first time. The key steps of the synthesis include an asymmetric Diels-Alder reaction, a Pauson-Khand reaction, a Pd-catalyzed reductive hydrogenolysis reaction, and an oxidative heterocoupling reaction. These reactions enabled the synthesis of (+)-propindilactone G in only 20 steps. As a consequence of our synthetic studies, the structure of (+)-propindilactone G has been revised.
An asymmetric total synthesis of
(−)-spirochensilide A has
been achieved for the first time. The synthesis features a semipinacol
rearrangement reaction to stereoselectively construct the two-vicinal
quaternary chiral centers at C8 and C10, a tungsten-mediated cyclopropene-based
Pauson–Khand reaction to install the C13 quaternary chiral
center, and a furan-based oxidative cyclization to stereoselectively
form the spiroketal motif.
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