ChemSpider ID 9040059 | ||
 | ||
Appearance White to off-white powder or crystals | ||
Phanephos is an organophosphorus compound with the chemical formula (C2H4)2(C6H3PPh2)2 (Ph = C6H5). It is a white solid that is soluble in organic solvents. It is an example of a chiral diphosphine used in asymmetric hydrogenation. Many substituents have been introduced in place of the phenyl groups, e.g., i-Pr, C6H11, etc and a variety of chiral phosphine ligands have been reported in asymmetric catalysis since the 1960s.
Contents
Preparation
Phanephos can be prepared by two steps from [2.2]paracyclophane. In the first step, [2.2]paracyclophane is dibrominated to give a pseudo-para dibromide. Thermal isomerisation then gives pseudo-ortho atropisomer of dibromide. This isomer is subjected to lithium-halogen exchange by nBuLi and the resulting dilithium compound is treated with PPh2Cl to give a racemic mixture of Phanephos.
Uses
Phanephos has been used in rhodium- and ruthenium- mediated stereoselective hydrogenation of dehydro amino acid methyl esters and asymmetric reduction of various β-ketoesters with about 90 % ee.