Diversity Oriented Synthesis of Chiral Hexacoordinated Phosphate Anions

Abstract

Novel hexacoordinated phosphate anions consisting of a central phosphorus(v) atom and at least one tetrachloropyrocatechol ligand can be simply prepared in modest to decent yields (37−71%) as their dimethylammonium salts following a one‐pot process and with simple, usually commercially available, starting materials. A variety of symmetrical diones (α‐diketones or ortho‐quinones) can be used in this protocol and the structurally‐diverse products are chemically stable when two tetrachloropyrocatechol ligands surround the P atom. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Chiral anion-mediated asymmetric ion pairing chemistry

“…30 This procedure involves the in situ formation of a spirophosphorane intermediate which reacts with essentially any diols to generate, in one-pot, mixed hexacoordinated phosphate anions containing two tetrachlorocatecholate and a third different diol ligands. 31 The protocol can be scaled-up to multi-gram quantities and yields are reproducible. With ligands, such as BINOL, the diastereoselectivity of the reaction is often high (496%).…”

Hexacoordinated phosphates: how to teach old chiral anions new asymmetric tricks

“…The synthesis of functionalized /mixed hexacoordinated phosphate anions containing two tetrachlorocatechols and a third different 1,2‐diolato ligand can also be achieved. However, the preparation of such P(VI) anions is not a trivial matter 11. A practical and general synthetic procedure had to be developed for the making of such novel hexacoordinated phosphates; anion Bis(tetrachlorobenzenediolato)mono([1,1′]binaphthalenyl‐2,2′‐diolato) phosphate(V) anion (BINPHAT) 4 (Scheme ), which includes a BINOL moiety, is the archetype of such derivatives 12.…”

“…It is feasible, although with some risks, to change the oxidant ( o ‐chloranil) in this process for another ortho ‐quinone, but original phosphate anions such as phenanthroline derivative 6 can result from the operation (see Scheme ) 11. The one‐pot procedure can be extended to the making of other mixed phosphates by varying the nature of the diol added last in the protocol (e.g., mannose, tartrate, dihydrobenzoin derivatives 7 – 9 ) (Scheme ) 13,15…”

Sugar derived hexacoordinated phosphates: Chiral anionic auxiliaries with general asymmetric efficiency

“…Methyl 4,6-O-benzylidene-a-D-allopyranoside 6 was obtained from 5 by (i) benzylic protection of the hydroxyl group at C7, (ii) oxidation of the alcohol at C8, and (iii) treatment with NaBH 4 to afford the axial alcohol at C8 and the concomitant deprotection of C7. With these diols in hands, the synthesis of the respective phosphate anions was attempted following the guidelines reported earlier in our group (Scheme 1): 61 Anhydrous tetrachlorocatechol and P(NMe 2 ) 3 were refluxed in toluene. After concentration in vacuo, successive additions of o-chloranil (3,4,5,6-tetrachloro-3,5-cyclohexadiene-1,2-dione) and then of diols 4, 5, and 6 in CH 2 Cl 2 were performed to achieve the preparation of the anions.…”