Pentacoordinated molecules. 92. Diequatorial and axial-equatorial orientations of eight-membered rings in monocyclic pentaoxyphosphoranes containing trifluoroethoxy groups

Neutral Six-Coordinate Phosphorus

“…101 Hydrolysis of compounds such as 42d to phosphates have been studied and the reactivity of related compounds were also analyzed. 107 Related neutral hexacoordinated phosphorus compounds of this system, obtained when two X groups of 42b were replaced by either a 2,2′-biphenoxy group or a saturated alkane diol giving 61 are described below in section D.…”

Tailor-Made Supramolecular Chirogenic System Based on Cs-Symmetric Rigid Organophosphoric Acid Host and Amino Alcohols: Mechanistic Studies, Bulkiness Effect, and Chirality Sensing

“…The rigid PA 3 consists of two cis -fused dihydrofurofuran D rings, one eight-membered carbocyclic C ring, and one dioxaphosphocine H ring. The newly formed H ring can adopt either boat–boat or boat–chair conformation . Combination of C and H rings in boat and boat–chair conformations (Figure a) is preferred over boat and boat–boat conformations (Figure b) to decrease transannular steric clashes between the oxygen on the P atom with the H atom at the methylene carbon.…”

“…The purity of 3 was established by 31 P NMR, showing a single peak at δ = −15.5 ppm. The 1 H NMR showed long-range 5 J P–H coupling for the proton at δ = 4.83 ppm, with the P atom revealing coupling at J = 2.4 Hz, further confirming the boat–chair conformation of the H ring . The σ- plane of C s -symmetric PA 3 passes through the center of the molecule via the P atom (Figure c).…”

Experimental and theoretical conformation analysis of eight-membered silocines with planar fragments

“…The experimental and theoretical (DFT B3LYP/6-31G*) conformation analysis of eight-membered 1,3,2-dioxasilocines having planar fragments showed that these compounds in solution exist as boat-chair, boat-boat, or twist-boat conformers, depending on the presence of unsaturated planar fragment, nature of the heteroatom in position 6 of the eight-membered ring, and substituents on the silicon atom.I-IV, X = S: I, R 1 = R 2 = t-Bu, R 3 = H, R 4 = Me; II, R 1 = Me, R 2 = t-Bu, R 3 = R 4 = Me; III, R 1 = R 2 = t-Bu, R 3 R 4 = (CH 2 ) 4 ; IV, R 1 = Me, R 2 = t-Bu, R 3 = CH 2 =CH, R 4 = Ph;V, X = S=O, R 1 = R 2 = R 3 = Me, R 4 = Ph.Steric structure of eight-membered heterocyclic systems has been studied in sufficient detail by X-ray diffraction and NMR spectroscopy [1][2][3][4]. New polyfunctional eight-membered heterocyclic systems are sought for, taking into account that some of them possess useful properties [5][6][7].…”

“…Steric structure of eight-membered heterocyclic systems has been studied in sufficient detail by X-ray diffraction and NMR spectroscopy [1][2][3][4]. New polyfunctional eight-membered heterocyclic systems are sought for, taking into account that some of them possess useful properties [5][6][7].…”