title: 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]}2 or 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), two cyclo-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 a trans arrangement, whereas the other C-C-O-P torsion angle is 92.48 (16)°, showing a gauche conformation. Both six-membered POCCCO rings have good chair-shape conformations. In both the trans and gauche conformations, the catechol O atoms are in the axial sites and the short P=O bonds are equatorially bound.
authors.affiliation: Chemistry Department, Taibah University, PO Box 30002, Code 14177, Al-Madinah Al-Munawarah, Kingdom of Saudi Arabia.
authors.forename: Musa A
authors.initials: MA
authors.lastname: Said
authors.affiliation: Chemistry Department, Taibah University, PO Box 30002, Code 14177, Al-Madinah Al-Munawarah, Kingdom of Saudi Arabia.
authors.forename: Adeeb Al Sheikh
authors.initials: AA
authors.lastname: Ali
authors.affiliation: School of Chemistry, University of East Anglia, Norwich NR4 7TJ, England.
authors.forename: David L
authors.initials: DL
authors.lastname: Hughes
keywords: 1,3,2-dioxaphosphinane; N-chlorodiisopropylamine (NCDA); crystal structure; phosphate ester; podand-type ligands