4-Vinylbenzodioxinones as a new type of precursor for palladium-catalyzed (4+3) cycloaddition of azomethine imines

Palladium-catalyzed [3 + 2] cycloaddition of 4-vinyl-4-butyrolactones with sulfamate-derived cyclic imines: construction of sulfamate-fused pyrrolidines

The palladium-catalyzed [3 + 2] decarboxylative cycloaddition of 4-vinyl-4-butyrolactones with sulfamate-derived cyclic imines has been developed, providing the sulfamate-fused pyrrolidine derivatives in high yields with good diastereoselectivities. The scale-up reaction and further derivation of the product worked well, demonstrating the potential application of the current reaction in organic synthesis. A plausible reaction mechanism was also proposed.

Quinazoline-Derived Azomethine Imines as Substrates To Access Polycyclic Compounds

Quinazolines are essential structural constituents of many pharmaceuticals and bioactive natural products. Quinazoline-derived azomethine imines (QAIs) have emerged recently as valuable building blocks for the synthesis of various quinazoline derivatives. This Synopsis presents recent advances in (formal) cycloaddition reactions of QAIs for the synthesis of quinazoline-fused 5- to 8-membered heterocycles as well as three-dimensional compounds.

Palladium-Catalyzed [3 + 2] Cycloaddition of 4-Vinyl-4-Butyrolactones with Alkenes: Synthesis of Spirocyclopentane Compounds

A palladium-catalyzed [3 + 2] cycloaddition of 4-vinyl-4-butyrolactones (VBLs) with alkenes has been developed to afford various spirocyclopentane products in high yields with excellent diastereoselectivities. The scale-up reaction and further derivations of the product worked well, demonstrating the potential application of the current reaction in organic synthesis.

Pd-catalyzed sequential intramolecular annulation/intermolecular [3+2] cycloaddition of 5-allenyloxazolidine-2,4-diones with dipoles: synthesis of spiroheterocycles

Pd-catalyzed sequential intramolecular annulation/intermolecular [3+2] cycloaddition of 5-allenyloxazolidine-2,4-diones with dipoles was achieved. Under palladium catalysis, various 5-allenyloxazolidine-2,4-diones reacted with 1,3-dipoles such as nitrile N-oxides, azomethine imines or nitrilimines to give a series of functionalized spiroheterocycles in high yields. The scale-up reaction and further derivation of products were successful. A plausible mechanism was also proposed based on the control experiments.

Ru(II)-Catalyzed C-H Activation/[4+2] Annulation of Sulfoxonium Ylide with Maleimide: Access to Fused Benzo[e]isoindole-1,3,5-trione

A ruthenium-catalyzed C-H activation and a concomitant [4+2] annulation of sulfoxonium ylide with maleimide have been demonstrated. This tandem reaction results in the formation of fused benzo[e]isoindole-1,3,5-trione. The method employs mild conditions and is free of metal oxidants. The reaction pathway predominantly involves protodemetalation over β-hydride elimination due to the lack of syn β-hydrogens.

Polycyclic Pyrazolidines by Tandem Diazomalonate Dipolar Cycloadditions and CpRu-Catalyzed Carbene Additions

Thanks to the ability of diazo derivatives to react either as 1,3-dipoles and as carbenes after dinitrogen extrusion, combinations of oxa or aza benzonorbornadienes and diazomalonates afford polycyclic pyrazolidines via a three-step sequence of (i) a highly diastereoselective [3+2]-cycloaddition, (ii) a CpRu-catalyzed carbene addition, and (iii) a second dipolar cycloaddition. Of importance, step (II) represents a unique access to novel bench-stable N,N-cyclic azomethine imines, which behave as effective 1,3-dipoles in combination with electron-poor dipolarophiles. Each step proceeds efficiently and the 3-step process can be performed in one-pot to yield a polycyclic pyrazolidine in excellent overall yield (90 %).

Palladium-Catalyzed (4 + 1) Annulation of 4-Vinylbenzodioxinones with Sulfur Ylides: Diastereoselective Synthesis of Dihydrobenzofuran Derivatives

Palladium-catalyzed (4 + 1) annulation of 4-vinylbenzodioxinones with sulfur ylides has been developed to afford various dihydrobenzofuran derivatives in moderate to high yields with excellent diastereoselectivities. The scale-up reaction and further derivations of the product worked well, demonstrating the application potential of the current reaction in organic synthesis.

Palladium-Catalyzed Enantioselective [4+2] Cycloaddition of 4-Vinylbenzodioxinones with Barbiturate-Derived Alkenes: Con-struction of Chiral Spirobarbiturate-Chromanes

In this paper, Pd-catalyzed [4+2] decarboxylative cycloaddition of 4-vinylbenzodioxinones with barbiturate-derived alkenes has been developed, leading to various spirobarbiturate-chromane derivatives in high yields with excellent diastereo- and enantioselectivities. The scale-up reaction and further derivation of the product were demonstrated. A plausible reaction mechanism was also proposed.