Lewis acid-promoted [2+1] cycloaddition reactions of a 1-seleno-2-silylethene to 2-phosphonoacrylates:: Stereoselective synthesis of a novel functionalized α-aminocyclopropanephosphonic acid

Stereoselective SnCl4-promoted [2 + 1] cycloaddition reactions of 1-seleno-2-silylethene 1 with 2-phosphonoacrylates 2 lead to highly functionalized cyclopropanephosphonate esters 3 in high yields. The cyclopropane products 3 are potentially versatile starting materials for biologically important compounds. Stereoselective synthesis of a novel functionalized alpha-aminophosphonic acid derivative, an analogue of (Z)-2,3-methanohomoserine 13, from the cycloadduct 3b was achieved. Stereoselectivity in the [2 + 1] cycloaddition was explained by consideration of the structure of the 2-SnCl4 complex.