2-Hydroxy-5-methyl-2-oxo-6-phenyl-4-phosphonomethyl-1,4,2-oxazoniaphosphorinane

Absolute Configuration and Conformation of (−)-R-t-Butylphenylphosphinoamidate: Chiroptical Spectroscopy and X-ray Analysis

“…The angles between the O2–C21 and O3–C31 bonds and least-squares ring planes C21–C22–C23–C28–C29–C30 and C31–C32–C33–C38–C39–C40 are 2.47° and 0.60°, respectively. The length of the P1O1 bond is 1.499(1) Å, which is longer than the typical PO value of 1.489 Å found in similar compounds, 1.488 Å found in aminophosphoric acids, and 1.487 Å found in triphenyl phosphinoxide (C 6 H 5 ) 3 PO . Such an elongation of the PO bond could speak for the polarization effect of the double PO bond whose length becomes intermediate between the double PO and single P + –O – bonds.…”

“…The methyl carbon atoms C2, C3, and C4 of the tert-butyl group adopt the following conformations in respect to the oxygen O1 atom: -ap (φ = −175.83(11)°), +sc (φ = 63.92(12)°), and −sc (φ = −54.52(13)°), respectively. In respect to the nitrogen N1 atom, these groups have the following positions: +sc (φ = 57.13( 14 1) Å, which is longer than the typical PO value of 1.489 Å found in similar compounds, 27 1.488 Å found in aminophosphoric acids, 28 and 1.487 Å found in triphenyl phosphinoxide (C 6 H 5 ) 3 PO. 29 Such an elongation of the P O bond could speak for the polarization effect of the double PO bond whose length becomes intermediate between the double PO and single P + −O − bonds.…”

Structure-directing weak phosphoryl XH...O=P (X = C, N) hydrogen bonds in cyclic oxazaphospholidines and oxazaphosphinanes

“…The lowest distance is 2.282 Å for refcode SIMTUD (Seidel et al, 1990), which is approximately as short as the shortest distances in Table 2, taking into account the variability for which the proton positions are determined. The oxazaphosphinane series has only nine observations with a mean HÁ Á ÁO distance of 2.248 Å , with some low NHÁ Á ÁO P distances of 1.789 and 2.021 Å for refcodes HIQLIC (Saint-Clair et al, 1999) and FEWHOE (Makaranets et al, 1987), respectively. The tendency towards lower HÁ Á ÁO P is equally well observed in the three oxazaphosphinane structures of this paper.…”