Thermal Rearrangement of Trichloroacetimidic Esters of Allylic α-Hydroxyphosphonates: A Convenient Way to (3-Amino-1-alkenyl)phosphonic Acids

All articles of this category Secondary dialkyl (1-hydroxy-2-alkenyl)phosphonates 3 are reacted with trichloroacetonitrile to yield the new (1-dialkoxyphosphoryl-2-alkenyl) 2, 2,2-trichloroacetimidates 4 , which in boiling toluene (for compounds 4b-g ) or xylene (for 4a ) are transformed regiospecifically to the 2,2, 2-trichloro- N -(3-dialkoxyphosphoryl-2-alkenyl)-acetamides 5 . The [3,3] sigmatropic rearrangement of compounds 4 occurs with high E -stereoselectivity (compounds 5a-e , and g ), or stereospecifically [( E )- 5f ]. Deprotection of the rearrangement products 5 with hydrochloric acid/propylene oxide affords the (3-amino-1-alkenyl)phosphonic acids 6 in excellent overall yields.