Phosphine-Catalyzed Ring-Opening Regioselective Addition of Cyclopropenones with Amides.

A series of amides, including α-bromo hydroxamates, -alkoxyamides, and -aryloxyamides, were subjected to phosphine-catalyzed ring-opening -selective addition with cyclopropenones, producing various special -unsaturated esters containing oxime ether motif, in moderate to excellent yields, with high regioselectivity, and exclusive -selectivity. The methodology is highly atom-economical, with simple operation procedures, and compatible with a wide substrate scope (more than 44 examples).

Phosphine-catalyzed dearomative [3+2] cycloaddition of 4-nitroisoxazoles with allenoates or Morita-Baylis-Hillman carbonates.

An efficient phosphine-catalyzed dearomative [3+2] annulation of 4-nitroisoxazoles with allenoates or Morita-Baylis-Hillman carbonates has been established for the convenient synthesis of bicyclic isoxazoline derivatives. This reaction approach showed a broad substrate scope, high functional group compatibility, and excellent regioselectivity and diastereoselectivity. Furthermore, the success at the gram-scale and synthetic applications of the obtained compound 3a demonstrate the great potential of this methodology for practical applications in organic synthesis.