Hui Xiong

Efficient preparations of novel ynamides and allenamides

Abstract Practical syntheses of a series of novel ynamides and allenamides are described here. While a base-induced isomerization protocol of propargyl amides leads to an array of chiral and achiral allenamides, ynamides are prepared from enamides via bromination followed by base-induced elimination of the Z -bromoenamides. These ynamides and allenamides possess improved thermal stability compared to ynamines and allenamines. They can be isolated, purified, and handled with ease, and thus, should be synthetically more useful than traditional ynamines and allenamines.

Chiral enamide. Part 1: Epoxidations of chiral enamides. A viable approach to chiral nitrogen stabilized oxyallyl cations in [4+3] cycloadditions

Abstract The first study of stereoselective epoxidations of chiral enamides is described here. Its potential in the synthesis of chiral α-keto aminals as a viable approach to nitrogen stabilized oxyallyl cations in stereoselective [4+3] cycloadditions is also illustrated.

Inverse demand [4+2] cycloaddition reactions of allenamides: Reactivity scopes of an electron deficient variant of allenamines

Abstract The synthesis and reactivity of a series of new allenamides are described. These electron deficient variants of allenamines are more stable than allenamines but possess comparable reactivity. Particularly, oxazolidinone and imidazolidinone substituted allenamides undergo efficient inverse demand [4+2] cycloaddition reactions with heterodienes, leading to unique pyranyl heterocycles. The reactivity differences between various allenamides containing different substitution patterns around the nitrogen atom are illustrated.