140633-12-1Relevant articles and documents
Synthesis of nonracemic dimethyl α-(hydroxyfarnesyl)phosphonates via oxidation of dimethyl farnesylphosphonate with (camphorsulfonyl)oxaziridines
Cermak, Diana M.,Du, Yanming,Wiemer, David F.
, p. 388 - 393 (2007/10/03)
Several strategies for synthesis of nonracemic dimethyl α- (hydroxyfarnesyl)phosphonate and the parent phosphonic acid have been explored. Separation of diastereomeric derivatives prepared by esterification of racemic α-hydroxy phosphonate with (S)-(+)-O-methylmandelic acid was possible, and these diastereomers could be assigned absolute stereochemistry on the basis of literature precedent. However, hydrolysis to the α-hydroxy phosphonic acid was accompanied by extensive isomerization. Addition of a nonracemic phosphonamidite to farnesal also gave nonracemic material, but again hydrolysis was problematic. Oxidation of dimethyl farnesylphosphonate anion with nonracemic (camphorsulfonyl)oxaziridines was shown to be regio- and stereoselective for formation of the α-hydroxy phosphonate. Enantiomeric excess of ~70% ee was established by conversion of the oxidation products to their (S)-(+)-O-methylmandelate derivatives. Although hydrolysis of these methyl esters was accompanied by extensive racemization, both enantiomers of α-(hydroxyfarnesyl)phosphonic acid were obtained in low ee by this strategy.
