Synthesis of Phosphaformamidines and Phosphaformamidinates

Abstract

A large-scale synthetic route to a variety of phosphaformamidines and phosphaformamidinates, a type of derivative that was not accessible by the methods previously known for preparing phosphaamidines and phosphaamidinates, is reported. Thermally stable ethyl N-arylformimidates 1 (ArN=CH(OEt), Ar = 2,4,6-(Me)3Ph or 2,6-(iPr)2Ph) readily reacted with lithium dialkyl- and diarylphosphanides to afford the corresponding N-aryl phosphaformamidines in 80 and 60% yield, respectively, whereas with lithium (aryl)(silyl)phosphanide, the N-aryl-N-silylphosphaformamidine (60% yield) was obtained. Addition of primary lithium arylphosphanides to 1 followed by addition of a stoichiometric amount of nBuLi gave rise to the respective phosphaformamidinates (70-88% yield). Methanolysis of the products afforded the N-aryl-N-hydrogenophosphaformamidines (90-95% yield). The solid-state structure of one of the phosphaformamidinates is also presented.

Facile Synthesis of Phosphaamidines and Phosphaamidinates using Nitrilium Ions as an Imine Synthon

“…[12] Iminophosphanes (i.e., phosphaamidines C), in contrast, offer an easily tunable imine fragment which allows facile steering of the steric and electronic properties of the ligand, but they are difficult to access. So far, only four examples were prepared by reacting an imidoyl chloride [13,14] with alkali-metal phosphides [15] or silylphosphanes. [16,17] Two additional reports mention the synthesis of bis(imino)phosphanes, but without conclusive analytical data.…”

Surprisingly Different Reaction Behavior of Alkali and Alkaline Earth Metal Bis(trimethylsilyl)amides toward Bulky N‐(2‐Pyridylethyl)‐N′‐(2,6‐diisopropylphenyl)pivalamidine

“…Furthermore, intramolecular steric strain in combination with soft alkali metals was also suspected to be responsible for this exceptional reaction behavior. Due to this consideration, we prepared the appropriate N ‐(2‐pyridylethyl)‐ N′ ‐(2,6‐diisopropylphenyl)formamidine ( 8 ) from Dipp‐NH 2 , HC(OEt) 3 , and 2‐PyCH 2 CH 2 NH 2 without solvent at 140 °C according to reaction 7; isolation and purification of intermediately formed Dipp‐N=CH‐OEt gave no significant improvement of the yields. Metalation of formamidine 8 with AN(SiMe 3 ) 2 in toluene yielded the corresponding metalation products [(thf)A{HC(=NDipp)(‐NCH 2 CH 2 Py)}] 2 [A=Na ( 9 a ), K ( 9 b )] after recrystallization from THF solution as depicted in reaction 7.…”

Experimental and Computational Studies of Anti‐Bredt Amidinium Salts

“…Melting points (uncorrected) were measured with an Electrothermal MEL‐TEMP apparatus. Ethyl N ‐arylformamidinates were synthesized from the corresponding aniline and triethylorthoformate, according to published procedures 24…”

“…Ethyl N-arylformamidinates were synthesized from the corresponding aniline and triethylorthoformate, according to published procedures. [24] Synthesis of N-1-adamantylformamide: [25] The preparation was improved by adapting the formylation procedure of Huffman. [26] A mixture of formic acid (4.5 mL, 120 mmol) and acetic anhydride (5.66 mL, 60 mmol) was stirred one hour at room temperature, and then added dropwise to a stirred solution of 1-adamantamine (6.86 g, 45.4 mmol) in dichloromethane at À78 8C.…”