α-Phosphanyl amino acids: synthesis, structure and properties of alkyl and heterocyclic N -substituted diphenylphosphanylglycines

N-Alkyl and N-heterocyclic substituted diphenylphosphanylglycines 1a–j were synthesized by a convenient one-pot, three-component reaction of diphenylphosphane, the corresponding primary amine and glyoxylic acid hydrate in diethyl ether. Phosphanylglycolates 2 and phosphoniobis(glycolates) 3 were detected as intermediates. In the case of steric hindrance or low basicity of the amine only 2 or mixtures of 2 and 1 are formed. Reactivity studies of selected phosphanylglycines showed facile decarboxylation and hydrolysis, oxidation and formation of coordination compounds with BH3 or W(CO)5. N-Alkyl derivatives (tert-butyl, n-hexyl, benzhydryl) with moderate steric hindrance reacted with Ni(COD)2 in THF or toluene in the presence of ethylene with heating under pressure to yield highly active oligomerization catalysts, and converting the ethylene to liquid and low-molecular-weight solid ethylene oligomers (MNMR 500–1250 g/mol) with high selectivity for linear α-olefins. Smaller N-alkyl or N-heterocyclic amino substituents at the phosphanyl acetic skeleton interfere with the ethylene conversion and deactivate the catalyst. The structures of the compounds were elucidated by solution NMR and single crystal XRD studies.