A new route for the synthesis of phosphate esters: 2,2′-[benzene-1,2-diylbis(oxy)]bis(5,5-dimethyl-1,3,2-dioxaphosphinane) 2,2′-dioxide

Abstract

Podand-type ligands are an interesting class of acyclic ligands which can form host–guest complexes with many transition metals and can undergo conformational changes. Organic phosphates are components of many biological molecules. A new route for the synthesis of phosphate esters with a retained six-membered ring has been used to prepare 2,2′-[benzene-1,2-diylbis(oxy)]bis(5,5-dimethyl-1,3,2-dioxaphosphinane) 2,2′-dioxide, C6H4{O[cyclo-P(O)OCH2CMe2CH2O]}2or C16H24O8P2, (1), 2-[(2′-hydroxybiphenyl-2-yl)oxy]-5,5-dimethyl-1,3,2-dioxaphosphinane 2-oxide, [cyclo-P(O)OCH2CMe2CH2O](2,2′-OC6H4–C6H4OH), (2), and oxybis(5,5-dimethyl-1,3,2-dioxaphosphinane) 2,2′-dioxide, O[cyclo-P(O)OCH2CMe2CH2O]2, (3). Compound (1) is novel, whereas the results for compounds (2) and (3) have been reported previously, but we record here our results for compound (3), which we find are more precise and accurate than those currently reported in the literature. In (1), twocyclo-P(O)OCH2CMe2CH2O groups are linked through a catechol group. The conformations about the two catechol O atoms are quite different,viz.one C—C—O—P torsion angle is −169.11 (11)° and indicates atransarrangement, whereas the other C—C—O—P torsion angle is 92.48 (16)°, showing agaucheconformation. Both six-membered POCCCO rings have good chair-shape conformations. In both thetransandgaucheconformations, the catechol O atoms are in the axial sites and the short P=O bonds are equatorially bound.