142840-32-2Relevant academic research and scientific papers
STEREOSPECIFIC INTRAMOLECULAR CYCLIZATION FOR ASYMMETRIC SYNTHESIS OF (Rp)- AND (Sp)-ENANTIOMERS OF 2-OCTYL- AND 2-PHENYL-4H-1,3,2-BENZODIOXAPHOSPHORIN 2-OXIDES
Wu, Shao-Yong,Casida, John E.
, p. 177 - 184 (2007/10/02)
Our earlier studies established that: 1) 2-octyl- and 2-phenyl-4H-1,3,2-benzodioxaphosphorin 2-oxides (octyl- and phenyl-BDPOs) induce delayed neuropathy in adult hens at 3 and 200 mg/kg, respectively; 2) phenyl-BDPO also significantly potentiates the acute toxicity of the insecticide malathion to mice; 3) the (Rp) and (Sp) enantiomers of these compounds, resolved on a mg scale by chiral HPLC, differ in potency by 92- and 137-fold, respectively, as inhibitors of neuropathy target esterase.In order to further study the stereospecificity in their toxic effects, the individual enantiomers of octyl- and phenyl-BDPOs are prepared here be a general method of asymmetric synthesis from the corresponding TLC-resolved diastereomeric precursors (Rp)- and (Sp)-methyl N- L-prolinates through acid-catalyzed intramolecular cyclization.This occurs under mild conditions in high yields and involves inversion of configuration at phosphorus.HPLC with the CHIRALCEL OC column established their absolute configurations, based on a previously-published assignment, and 97-100percent e.e. for (Rp)- and (Sp)-octyl- and phenyl-BDPOs. Key words: Asymmetric synthesis, 1,3,2-benzodioxaphosphorin 2-oxide, cyclization, NTE inhibitors, L-propinates, stereochemistry.
