Synthesis, characterization and resolution of racemic (2-methylsulfinyl)phenylphosphonic acid methyl ester via its cinchoninium salts

Resolution of Racemates and Enantioselective Analytics by Cinchona Alkaloids and Their Derivatives

“…Some recent examples (11)(12)(13)(14) of such resolutions are shown in Figure 13.6 [16][17][18][19].…”

“…19 HPLC enantioseparation of racemic dichloroprop 43 on the (DHQD) 2 PHAL-type CSP(61). Column (150 mm  4 mm i.d.…”

Asymmetric oxidation of sulfenates to sulfinates as a new route to optically active ortho-phosphorylated phenyl sulfoxides

“…As already pointed out, oily O-menthyl benzenesulfinates 3a and 3b could not be separated as pure diastereomers by flash chromatography. 11 we were able to assign the (S)-absolute configuration to the sulfoxide enantiomer (À)-6. It follows that the major dextrorotatory diastereomer 3b formed in the asymmetric oxidation of (À)-menthyl sulfenate 5 with NBS has an (R)-configuration at the sulfur.…”

“…The synthesis of diisopropyl 2-(sulfanyl)phenylphosphonate 1 has been described previously. 11 NMR spectra were recorded in CDCl 3 , unless otherwise stated, on Brü ker spectrometers at 250, 400 or 500 MHz. Chemical shifts d were indicated in ppm using TMS as the internal standard or H 3 PO 4 as the external standard for 31 P NMR spectra.…”

“…10 Among them, the resolution of a 2-sulfinylated phenylphosphonic acid monoester only gave us one enantiomerically pure sulfoxide. 11 As summarized in Scheme 1, the direct enantioselective oxidation of o-phosphonophenyl sulfides achieved under catalytic or stoichiometric conditions was found to occur with low to moderate selectivity. Moreover, studies on the diastereoselective oxidation of phenylsulfides which bear a defined chiral phosphonamido group 9,12 at the orthoposition (derived from trans-N,N 0 -dimethylcyclohexane-1,2-diamine), have shown that diastereoselection is variable, depending on the nature of the oxidizing reagent.…”