C2 Symmetry Enantiopure Phosphorothiates end Phosphorothioamidates Starting from 2,2',6,6'-tetrol-1,1'-biphenylene

A straightforward procedure for the preparation of enantiopure phosphorothioates and diastereopure phosphorothioamidates of 2,2',6,6'-biphenyltetrol is presented. Basic alcoholysis of compounds trans-3 and cis-3 proceeds in high diastereoselectivity to give only two of the six possible acyclic phosphorothioamidates 4a and 4b (or 5a and 5b). When diastereopure 4 and 5 are subjected to acid alcoholysis they lead to enantiopure cyclic phosphorothioates trans-6 and rrans-7, respectively. All compounds prepared are solid, air stable and possess a Cz symmetry axis. Due to restricted rotation around the Cl-CI' bond, compounds 4a, 4b, 5a, 5b, 6 and 7 exist as stable atropisomers at rt. However for compounds frans-3 and cis-3, the bridged biphenyl system intercorverts at rt with a half-life of 6 h. The structure of compounds rrans-2, trans-3, and 5a has been confirmed by X-ray analysis. Phosphorothioates and phosphorothioamidates can be tested as agrochemicals since these classes of compounds can inhibit acetylcholinesterase of many different insect species.