Isolation of cis and trans Isomers of Some Oxaphosphorinans.

Structural studies of phosphorinanes

“…listed in Tables 5 and 6) other than 1,3,2-dioxaphosphorinanes The first compound, 206, will be discussed in Part II, the remainder will be discussed by Y, Z type indicated in the Tables, 2-R-2-OXO-1,2-oxaphosphorinanes (XXV)The 2-substituent-2-oxo-l,2-oxaphosphorinanes 207a,b(119) 208a,b(119,120), 209a,b(119,121), 210a,b(119)(120)(121), Zlla^b(122), and 212a,b(123) all exist as isomer pairs. The general method of synthesis is reaction of dihalide (usually dibromide) with trimethylphosphite to produce the isomeric mixture from which isomers can usually be separated by gas chromatography(119)(120)(121)(122)(123). From infrared stretching frequencies the geometries of the C5 methyl groups of 207a,b and 208a,b were postulated Other Phosphorinane Compounds R(0)P XXV to be solely equatorial for a isomers and at least sometimes axial for b isomers.…”

“…The presence of a peak in the region of 585-650 cm"^ for each b isomer was assumed to be due to axial methyl, whereas the a isomers lacked such a band. The single phosphoryl stretching frequency for each a isomer was assumed to indicate a single conformer, whereas the two bands for the corresponding b isomers were taken as indicative of two conformers(119,120). The relative phosphorus and C5 geometries were assigned on the basis of the Auwers-Skita rule(124,125) which states that cis isomers of 1,4 and trans 1,3 substituted cyclohexanes have higher refractive indices and higher densities.…”