Cover Picture: Diastereoselective Total Synthesis of (±)‐Schindilactone A (Angew. Chem. Int. Ed. 32/2011)

Abstract

A traditional Chinese herbal medicine schindilactone A, has been synthesized for the first time by Y.‐F. Tang, J.‐H. Chen, Z. Yang, and co‐workers. In their Communication on they outline an approach involving ring‐closing metathesis for diastereoselective formation of the fully functionalized eight‐membered CDE rings, a thiourea/cobalt‐catalyzed Pauson–Khand reaction for the stereoselective construction of the F ring, and a thiourea/palladium‐catalyzed carbonylative annulation cascade to construct the GH rings.

Palladium-catalyzed cross-coupling reaction of azides with isocyanides

“…7 On the other hand, Pd-catalyzed coupling reaction of carbene/nitrene precursors with σ-donor/πacceptor ligands is an efficient route to active unsaturated intermediates. Although Pd-catalyzed carbene transfer reactions with carbon monoxide 8 , alkynes 9 , and isonitriles 10 to form ketenes, allenes, and ketenimines have been developed, direct Pd-catalyzed nitrene transformation with σ-donor/πacceptor ligands has rarely been explored. 7a,b,e Thus, we have paid much attention to Pd-catalyzed cross-coupling reaction of azides with isonitriles, which would be a high efficient strategy to access unsymmetric carbodiimides.…”

An Unprecedented Synthesis of 3,3‐Disubstituted Isochroman‐1,4‐diones Using Nitrones as Oxygen Atom Donors

“…In this reaction, the nitrone transfers an oxygen atom to the ruthenacycle intermediate, facilitating the formation of the furan, and gets extruded from the reaction as an imine [27]. Intramolecular oxygen atom transfer by nitrones catalyzed by gold has also been reported [28]. To further validate the mechanism, we had conducted separate control experiments using pyridine-N-oxide [29] and DMSO [30] as the oxidators instead of the nitrone.…”

Intramolecular Iodine‐Mediated Oxygen Transfer from Nitro Groups to C≡C Bonds

“…It seems that the iodine catalyst behaves in a way very similar to that in related gold-catalyzed oxygen functionality transfer reactions. [15] After the direct iodonium activation ( IV. Finally, abstraction of iodine by an anion leads to the aromatization of the isoxazole moiety and regeneration of the catalyst.…”

“…In almost all cases electrophilic cyclization results in incorporation of iodine in the final product, [13] whereas gold catalysis typically results in hydrogen at the same position, due to the protodeauration step required for catalyst regeneration. [15,16] The method presented here is a unique example of iodine-mediated ring closure of internal alkynes with-out the introduction of halogen or oxygen from the solvent into the newly formed ring. Moreover, the developed method can be used broadly for the preparation of fused isoxazoles through nitro-alkyne cycloisomerization of either electron-rich or electron-poor substrates.…”