Regiochemical Control in the Substitution Reactions of Cyclotriphosphazene Derivatives with Secondary Amines

Abstract

The substitution reactions of the monospiro and geminally disubstituted cyclotriphosphazene derivatives NPClR (R = OCH(CF)CHO (1a), SPh (1b), OCHCHCHO (1c), NHPh (1d), OCHCHCHNH (1e), NHBu (1f)) with two secondary amines (pyrrolidine and dimethylamine) were carried out to investigate geminal or non-geminal directing effects in mixed substituent cyclophosphazenes. The relative amounts of isomeric products, geminal and non-geminal trans or cis, was established quantitatively from the P NMR spectra of the reaction mixtures. Although secondary amines generally follow a non-geminal pathway in the reactions with hexachlorocyclotriphosphazene, in this work, the reactions of two different secondary amines with some NPClR (R = OCHCHCHNH, NHPh, NHBu) derivatives lead to the formation of geminal products. We have shown that this observation depends on the electron-donating properties of the PR groups. Isolated compounds were analyzed by standard techniques such as elemental analysis, mass spectrometry, and H andP NMR spectroscopy. The structures of compounds for which suitable crystals could be obtained were characterized by X-ray crystallography.

4‐triphenylmethylaniline substituted cyclotriphosphazene derivatives assisted by multiple phenyl rings

“…Besides, the double peak group belonging to the PCl 2 phosphorus atoms (δ = 22 ppm) in proton coupled 31 P NMR spectrum of the compound indicated 4‐triphenylmethylaniline groups (δ = −1 ppm) were bound as bis geminal (Figure 1c). This situation also proves that primary amines follow proton abstraction chloride elimination mechanism in substitution reaction, [ 7 ] even if they contain bulky groups. At the same time, compound 4 was characterized by single crystal X‐ray diffraction technique and its structure was confirmed (Figure 4).…”

“…In the case of primary amines, they attack to phosphorus atom on the cyclotriphospazene ring in both geminal and non-geminal positions, depending on the steric and electronic effects of the amine as well as the nature of the amine groups. [6][7][8][9] For these systems, there are two competing mechanistic pathways to which the amine group attacks: (a) the bimolecular pathway resulting in the non-geminal product, (b) a dissociative process providing the geminal product.…”

RhB-Embedded Mn-MOF with Cyclotriphosphazene Skeleton as Dual-Emission Sensor for Putrescine as well as Smart Fluorescent Response of Aromatic Diamines and Nitrophenol

“…Among them, LMOFs constructed with flexible heterocyclic poly­(carboxylic acid) ligands exhibited a higher competitiveness in the sensing field. For example, cyclotriphosphazene and nitrogen heterocyclic triazine ligands could construct LMOFs with multilevel channels and a novel topological structure due to their structural flexibility. − On the other hand, their skeleton structure has a large content of N and P heteroatoms, which can provide more contacting sites and chemical interaction possibilities . It is beneficial to combine them with a variety of guest molecules or analytes so as to effectively improve their sensing efficiency.…”

“…20−22 On the other hand, their skeleton structure has a large content of N and P heteroatoms, which can provide more contacting sites and chemical interaction possibilities. 23 It is beneficial to combine them with a variety of guest molecules or analytes so as to effectively improve their sensing efficiency. However, recent studies have indicated that single-emission LMOF-based fluorescent sensors can always be affected by instrument noise and external environment during the sensing process.…”

Nucleophilic Substitution of 2,2-Bis(arylthio)-4,4,6,6-tetrachlorocyclotriphosphazene with Ammonia, Phenoxide, and Thiophenoxide

“…In this article, we report nucleophilic substitution of 3 with ammonia, phenoxide, and thiophenoxide (Scheme 2). 16,17 They explained this selectivity from the view point of steric hindrance. On the other hand, since ammonia is very small and have high nucleophilicity, the second and the fourth ammonia were introduced at geminal position and more quickly than the first and the third ammonia, respectively, in which both SN1 and SN2 processes would proceed (Scheme 4).…”