Juan Du

[3 + 2] Cycloaddition of Oxazol-5-(4H)-ones with Nitrones for Diastereoselective Synthesis of Isoxazolidin-5-ones

In the presence of TMSCl, the [3 + 2] cycloaddition of oxazol-5-(4H)-ones with nitrones proceeded smoothly and furnished the desired isoxazolidin-5-ones with high diastereoselectivities in reasonable chemical yields. The chemical structure of the title compounds was firmly confirmed by X-ray single-crystal structure analysis.

Facile access to novel 1,2,4-oxadiazinan-5-ones via [3 + 3] cycloaddition of in situ generated azaoxyallyl cations with nitrones

In the presence of Na2CO3, azaoxyallyl cations in situ generated from α-halohydroxamates with nitrones readily underwent [3 + 3] cycloaddition, and gave rise to 1,2,4-oxadiazinan-5-one derivatives in 56–99% chemical yields. The chemical structure of the title compounds was unambiguously identified by X-ray single crystal structure analysis.

1,3-Dipolar [3 + 3] cycloaddition of α-halohydroxamate-based azaoxyallyl cations with hydrazonoyl chloride-derived nitrile imines

Promoted by Et3N, the 1,3-dipolar [3 + 3] cycloaddition of α-halohydroxamate-based azaoxyallylcations with hydrazonoyl chloride-derived nitrile imines occurred efficiently, and furnished desired products in acceptable chemical yields. The chemical structure of the title compounds was firmly confirmed by an X-ray single crystal structure analysis.

Construction of 2,3,4,5-tetrahydro-1,2,4-triazines via [4 + 2] cycloaddition of α-halogeno hydrazones to imines

In the presence of sodium carbonate, the [4 + 2] cycloaddition of α-halogeno hydrazones to imines proceeded readily, and furnished 2,3,4,5-tetrahydro-1,2,4-triazines in moderate to high chemical yields.

Diastereoselective and Enantioselective Synthesis of Barbiturate-Fused Spirotetrahydroquinolines via Chiral Palladium(0)/Ligand Complex Catalyzed [4 + 2] Cycloaddition of Vinyl Benzoxazinanones with Barbiturate-Based Olefins

Under the catalysis of chiral palladium(0)/ligand complex, the [4 + 2] cycloaddition between vinyl benzoxazinanones and barbiturate-based olefins proceeded readily and provided barbiturate-fused spirotetrahydroquinolines in up to 96% chemical yield with up to >99:1 dr and 97% ee. The absolute configuration of barbiturate-fused spirotetrahydroquinolines was clearly identified by X-ray single crystal structure analysis. The reaction mechanism was proposed to shed light on the enantioselective formation of barbiturate-fused spirotetrahydroquinolines.