Synthesis of Chiral 2,3-Dihydrofurans via One-Pot Pd-Catalyzed Asymmetric Allylic Cycloaddition and a Retro-Dieckmann Fragmentation Cascade.

An efficient method for the enantioselective synthesis of 2,3-dihydrofurans bearing a quaternary stereocenter has been developed via Pd-catalyzed asymmetric allylic cycloaddition and a retro-Dieckmann Fragmentation cascade. The asymmetric allylic cycloaddition of vinylethylene carbonates with 3-cyanochromone followed by base-assisted retro-Dieckmann fragmentation proceeded smoothly via a one-pot process to produce chiral 3,4-disubstituted 2,3-dihydrofurans in high yields with excellent enantioselectivities.

Pd-Catalyzed regio- and stereoselective allylic substitution of vinylethylene carbonates with 1,2,4-triazoles.

N 1-Substituted 1,2,4-triazoles are ubiquitous skeletons in medicinal agents, agrochemicals, and organic materials. Herein, an efficient and practical method for the synthesis of N1-allylated 1,2,4-triazoles via Pd-catalyzed allylic substitution of vinylethylene carbonates (VECs) with 1,2,4-triazoles has been developed. By using a catalyst generated in situ from Pd2(dba)3·CHCl3 and DPPE under mild conditions, the process allows rapid access to N1-allylated 1,2,4-triazoles bearing diverse functionalities in high yields with excellent N1-selectivities, linear-selectivities, and Z-stereoselectivities.

Enantioselective Synthesis of Isoxazoline N-Oxides via Pd-Catalyzed Asymmetric Allylic Cycloaddition of Nitro-Containing Allylic Carbonates.

A useful method for the enantioselective preparation of isoxazoline N-oxides via Pd-catalyzed asymmetric allylic cycloaddition of nitro-containing allylic carbonates has been developed. By using palladium complex in situ generated from Pd2(dba)3·CHCl3 and phosphoramidite L2 as a catalyst under mild conditions, the transformation afforded vinylated isoxazoline N-oxides in high yields with acceptably high enantioselectivities.

Pd-Catalyzed Asymmetric Allylic Cycloaddition of N-Containing Allylic Carbonates with Isocyanates.

An efficient method for the enantioselective synthesis of cyclic ureas has been developed through Pd-catalyzed asymmetric allylic cycloaddition of readily accessible nitrogen-containing allylic carbonates with isocyanates. By using a palladium complex in situ generated from Pd2(dba)3·CHCl3 and phosphoramidite L1 or L3 as a ligand under mild reaction conditions, the process afforded imidazolidinones and tetrahydropyrimidinones with high yields and high levels of enantioselectivities.

Pd-Catalyzed regio- and enantioselective allylic substitution with 2-pyridones.

An efficient method for the asymmetric synthesis of N-substituted 2-pyridones via Pd-catalyzed regio- and enantioselective allylic substitution of hydroxyl-containing allylic carbonates with 2-pyridones has been developed. By using a palladium complex in situ generated from Pd2(dba)3·CHCl3 and phosphoramidite L2 as a ligand, the process allowed rapid access to N-substituted 2-pyridones with complete chemo- and regioselectivities and good to high enantioselectivities.