Synthesis of bis(phosphinomethyl)amines via bis(hydroxymethyl)phosphonium salts. Isolation of 9,9-bis(hydroxymethyl)-9-phosphoniabicyclo[3.3.1]nonane hydrogensulfate and chloride salts, and the crystal structures of [PPh2(CH2OH)2]+ Cl? and [(C6H11)2PCH2]2NCHMePh

Abstract

Phosphines of the type PR2H reacted readily with formaldehyde in the presence of acid to afford high yields of bis(hydroxymethyl)phosphonium salts [PPh2(CH2OH)2]+X–, [P(C6H11)2(CH2OH)2]+X–, [[graphic omitted]H2]+X–, and [[graphic omitted]H2]+X–(X = Cl or HSO4). Treatment of the mixed isomers of the bicyclononane phosphonium cation [P(C8H14)(CH2OH)2]+ in boiling H2SO4 gave a [3.3.1] isomer, the [4.2.1] isomer undergoing decomposition. A single-crystal X-ray diffraction study has been carried out on the phosphonium salt [PPh2(CH2OH)2]+Cl–. The geometry around phosphorus is essentially tetrahedral, and there is hydrogen bonding between the hydroxyl groups and the chloride anion. Treatment of these phosphonium salts with triethylamine and a primary or secondary amine afforded aminomethylphosphines (R2PCH2)2NR′(R = Ph, R′= CHMePh, CHMeCO2Me, CHMeCO2Et, [graphic omitted]CMe2, CH2CH2OH or CH2CHCH2; R = C6H11, R′= CHMePh or CHMeCO2H; R2= C8H14, R′= CHMePh) or C8H14PCH2NEt2 in good yields. A single-crystal X-ray diffraction study has been carried out on [(C6H11)2PCH2]2NCHMePh.