Perfluorophenyl phosphonate analogues of aromatic amino acids: Synthesis, X-ray and DFT studies

Stereochemistry of the Kabachnik‐Fields Condensation of Terpenic Amino Oximes with Aldehydes and Dimethyl Phosphite

“…Molecular modeling using Density functional theory (DFT) is a well‐established compromise between the desired accuracy and computer resources needed. In the latest publications on the modeling of aminophosphonates using DFT calculations, one of the most popular hybrid exchange‐correlation functional B3LYP was used in combination with Pople split‐valence double‐zeta basis sets 6–31G(d), 6–31+G(d), and 6–31G(d,p) . However, when hydrogen bonding is studied by DFT calculations, Minnesota hybrid meta‐GGA exchange‐correlation functional M06‐2X and long‐range corrected hybrid density functional with empirical atom‐atom dispersion corrections ωB97X−D provide better results over B3LYP …”

“…[26] However, when hydrogen bonding is studied by DFT calculations, Minnesota hybrid meta-GGA exchange-correlation functional M06-2X and long-range corrected hybrid density functional with empirical atom-atom dispersion corrections ωB97XÀ D provide better results over B3LYP. [25] For using DFT in calculation of NMR chemical shifts and spin-spin couplings, we chose hybrid exchange-correlation functional PBE0 that worked well in the calculations of nitrogen derivatives of terpenes. [27]…”

“…These calculated data are in agreement with published results: 22-26 kcal/mol for NÀ H…..O=P in less sterically hindered aminophosphonates. [25] We also estimated frequencies of the highest energy normal vibrations (stretching vibrations of O À H and N À H) in the H-bonded dimers found. Since DFT calculations systematically overestimate the frequencies of normal vibrations, we performed a correction of the calculated data as follows.…”

Synthesis, structural studies and biological properties of some phosphono-perfluorophenylalanine derivatives formed by SNAr reactions

“…32 As part of our investigations, we have recently reported a convenient synthetic method for the preparation of a series of phosphonate analogues of phenylglycine, homophenylalanine, and phenylalanine that differ in the number and position of uorine atoms in the phenyl ring. 33,34 These studies were supported by single-crystal X-ray diffraction analysis and quantum chemical calculations that provided information concerning the conformational preferences both in the solid and isolated states. Indeed, some of the obtained aminophosphonates underwent intramolecular S N Ar reactions yielding indolinylphosphonates as minor products.…”

Microwave-assisted synthesis of α-aminophosphine oxides by the Kabachnik-Fields reaction applying amides as the starting materials

“…However, the synthesis of the starting materials, unsubstituted a-aminophosphonates by the Kabachnik-Fields reaction utilizing ammonia or its precursors is not easy. [44][45][46] It was also obvious for us that the amides exhibit a lower reactivity in the phospha-Mannich condensation than amines.…”