1609396-92-0Relevant academic research and scientific papers
Synthesis of N,P-Disecondary o-Arylphosphanylanilines via o-R1NHC6H4P(R)O2Et Precursors and Preliminary Study of Cyclocondensations with (EtO)3CH/NH4PF6
Aluri, Bhaskar R.,Ghalib, Mohammed,Jones, Peter G.,Frauendorf, Holm,Heinicke, Joachim W.
, p. 182 - 190 (2020)
N-Secondary o-aminophenylarylphosphinates were prepared by Pd-catalyzed cross coupling of aryl-P(OEt)2 with the corresponding o-bromoanilines and reduced with LiAlH4 to o-phosphanylanilines. For the N-mesityl compounds a two-step reduction was necessary because of competing P–N condensation reactions. Preliminary studies of cyclocondensations of o-(RPH)C6H4NHR1 with (EtO)3CH/NH4PF6 showed that, in contrast to benzimidazolium salts, accessible in this way from disecondary o-phenylenediamines, the homologous 1,3-benzazaphospholium salts are highly reactive and undergo instantaneous oxidative addition of EtOH, liberated in the condensation. The resulting 3-ethoxy-benzazaphospholinium salts, which for R = Ph, R1 = Np are relatively stable and were detected by NMR and HRMS, decompose to yield P-oxo-1,3-benzazaphospholine·xHPF6 salts, and for R1 = Me additionally the rearranged N-ethyl-P-oxo-benzazaphospholinium salt. Detection of triethylphosphate indicates partial acid-catalyzed conversion of PF6– with EtOH. Alternative cyclocondensation of o-(MesPH)C6H4NHNp with excess Me2NCH(OMe)2 in the presence of HCl/Et2O led to the 2-methoxy-, or after removal of MeOH under vacuum to the corresponding 2-dimethylamino-1,3-benzazaphospholine. The structure elucidation of the new compounds is based on multinuclear NMR data and confirmed for an o-anilinophenylphosphinate by crystal structure analysis.
Benzazaphospholine-2-carboxylic acids: Synthesis, structure and properties of heterocyclic phosphanyl amino acids
Ghalib, Mohammed,Lach, Joanna,Fomina, Olga S.,Yakhvarov, Dmitry G.,Jones, Peter G.,Heinicke, Joachim
, p. 10 - 16 (2014/05/20)
1,3-Dialkyl-1,3-benzazaphospholine-2-carboxylic acids 2a,b can be conveniently prepared by metalation and alkylation of N-methyl- and N-neopentyl-o-phosphanylaniline in liquid ammonia and cyclocondensation of the resulting N,P-disecondary phosphanylanilines 1a,b with glyoxylic acid hydrate (GAH) in ether. The primary neopentylphosphanylaniline reacts with two equivalents of GAH and forms a phosphanylbis(amino acid) 3 with toluidine. α-Branched P-substituents induce strongly preferred formation of trans-diastereoisomers with R,R- and S,S-configuration at P and C2, as shown by a crystal structure analysis of 2a, whereas a P-neopentyl (P-Np) group gives rise to trans/cis-diastereoisomeric mixtures. The trans-configuration exhibits the P lone-pair in cis-position to the COOH group, suitable for formation of five-membered chelate rings, as in diphenylphosphanylacetate nickel catalysts for ethylene oligomerization. Screening of 2a,b/Ni(COD)2 solutions in THF by a batch procedure indeed showed formation of catalysts for conversion of ethylene to linear oligomers and waxy low-molecular weight polymers. The conversion depends strongly on the size of the N-alkyl group, being slow and limited for the N-Me catalyst 2a/Ni and much faster and more complete for the N-Np-substituted catalysts 2b/Ni and 2c/Ni (N-Np, P-tBu). Comparison of 2b/Ni with 2c/Ni shows that the more bulky P-substituent further increases the catalyst activity.
