Taxpropellane: A Novel Taxane with an Unprecedented Polycyclic Skeleton from the Needles of Taxus canadensis

Abstract

Taxpropellane, the first example of a taxane with an unprecedented 6/5/5/6/4/5‐membered ring hexacyclic skeleton ([3.3.2]propellane), was isolated from the needles of Taxus canadensis. This compound would be derived from a normal 6/8/6 taxane by a [2+2] cycloaddition reaction between the 3,4‐ and 11,12‐double bonds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Four‐Membered Cycle Formation Challenge: GaCl3‐Promoted Formal [2+2]‐Cycloaddition of Donor–Acceptor Cyclopropanes to Bicyclobutylidene

“…It should be noted that, despite the seeming originality, [3.3.3] and even [2.3.3]propellane systems occur in structures of natural compounds, albeit they are rare (Figure ). Natural propellanes show a considerable spectrum of biological activity, including anti‐cancer properties . Modhephene is one of the most famous ones, and a number of full syntheses of this compound have been performed by various scientific groups , .…”

General Synthetic Approach to Diverse Taxane Cores

“…It is proposed that, biosynthetically, this type of cycloaddition forges the cyclobutane motif embedded in 4 and 5 from similar, albeit slightly more oxidized, precursors compared to 14. 60,61 Nonetheless, we envisioned that taxol core 14 would serve as an effective model substrate�in lieu of a more oxidized skeleton�to probe the feasibility of this reaction. We were pleased to find that with simple blue LED irradiation (centered at ∼460 nm) at room temperature, the taxol core readily underwent the desired cycloaddition to deliver the cyclotaxane core (13) in a remarkable 98% yield.…”

Occurrence, synthesis and applications of natural and designed [3.3.3]propellanes

“…36 Two similar [3.3.2]propellanes with resembling chemical structures were also isolated from the same species. 37,38 The complex structure of the taxane-derived canataxapropellane was elucidated using high resolution mass spectrometry and 2D NMR studies. A plausible biosynthetic pathway was proposed based on taxinine A (21), which was previously isolated from the same species.…”