S -2-chloropropionate

In conclusion, the first reaction yields much more (S)-2-chloropropionic acid, although the enantiomeric ratio of this reaction is much lower. 

Houpis, I.N., Patterson, L.E., Alt, C.A., Rizzo, J.R., Zhang, T.Y. and Haurez, M. S3mthesis of PPAR Agonist via Asymmetric Hydrogenation of a Cinnamic Acid derivative and Stereo-specific Displacement of (S)-2-Chloropropionic Acid. Org. Lett. 2005, 7, 1947-1950. 

The phenoxypropionic acid herbicides (Chapter 31) rely on an SN2 reaction to convert the S-2-chloropropionic acid (1) to the ff-2-aryloxy derivative 2.3 These compounds are also available from lactic acid by substitution reactions -lactic acid (3) requires two inversions, whereas S-lactate (4) only requires one (Schemes 22.2 and 22.3).4... 

Figure 1. CD spectra obtained within the n- ir band system of benzophenone upon dissolution in (a) methyl-(S)-2-chloropropionate, (b) (K)-a-phenylglycinol, and (c) (2R,3J )-2,3-butanediol (data adapted from reference [4]).

Another chiral small molecule, (S)-2-chloropropionic acid (S-CPA), is a key intermediate in the synthesis of the 2-phe-noxypropionic acid class of herbicides, including Fusilade (Avecia) and Mecoprop (BASF). Kinetic resolution of racemic CPA is performed with a whole cell biocatalyst expressing a dehalogenase enzyme selective for the (R)-enantiomer and producing (S)-lactic acid, itself a useful byproduct. The (S)-chloropropionic acid is extracted with a... 

S)-2-chloropropionic acid by enantioselective dehalogenation racemate (R)-specific dehalogenase... 

A -(l-(S)-Ethoxycarbonyl-3-phenylpropyl)-L-alanyl-N-carboxyanhydride C16H19NO5 Ethyl (S)-(—)-2-chloropropionate C5H9CIO2... 

For a solvent such as acetonitrile that is a poor donor (D.N. = lU.l) (7.), the variable temperature CD spectra of the (S)-2-chloropropionate complex (Figure 9) can be understood in terms of the shift in the equilibrium towards the energetically preferred rotamer I at low temperature. This shift in the equilibrium is heightened by the increase in the dielectric as the temperature is lowered. The CD spectra in water and methanol also become more negative as the temperature is lowered. 

Etherification of 4-hydroxyacetophenone in dimethyl sulphoxide containing potassium carbonate by the slow addition of methyl (S)-2-chloropropionate over 30 mins, and reaction with stirring during 6 hours at ambient temperature (with introduction of more potassium carbonate over a further 5 hours) gave methyl (R)-2-(4-acetylphenoxy)propionate (enantiomeric excess, 86%). 

Dissolve it in Et20, dry (CaCl2), evaporate and distil it through a short colimm. Distillation through a Podbielniak colitrrm (see S -(-)-2-chloropropionic acid below) led to decomposition. Store it in the dark under N2, preferably in sealed ampoules. Even at-10° it slowly decomposes. LACHRYMATORY. [Fuel et al. JA/n Chem Soc 76 6054 1954, Beilstein 2 IV 761.]... 

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