Thermal Retro-Trimerization of Some 1,3,5,2,4,6-Trioxatriphosphorinanes to Phosphenites
作者:Louis D. Quin、Alexey S. Ionkin
DOI:10.1021/jo00121a042
日期:1995.8
Pyrolysis in a packed tube of the vapor from three 2,4,6-tris(aryloxy)-1,3,5,2,4,6-trioxatriphosphorinanes was performed at 300-350 degrees C and 10(-6) mm; the product was collected on a cold finger chilled by liquid nitrogen. The cracking of the trimer was complete, and the product at -195 degrees C appeared to consist only of the monomeric aryl phosphenite, ArOP=O. On warming, dimerization occurred, later followed by trimer formation. The weak P-31 MMR signal for the phosphenite (about delta 238 for three O-aryl derivatives) persisted in the solution for several weeks if water was rigorously excluded. Treatment of the phosphenite with water or alcohols at -195 degrees C gave a mixture of products; the major product (ArO-PH(O)OH) came from addition of the nucleophile to the P=O bond, but significant amounts (10-20%) of dialkyl H-phosphonates (HP(O)(OR)(2)) were present, apparently from displacement of the O-aryl substituent of the phosphenite, followed by addition to the double bond.