REFERENCES AND NOTES
- Kaye , P. T. and Ravindran , S. S. 1995 . S. Afr. J. Chem. , 48 : 64
- Evans , M. D. PhD . 1998 . thesis Rhodes University .
- Evans , M. D. and Kaye , P. T. 1999 . Synth. Commun. , 29 : 2137
- Analogous phenoxyacetate esters have also presented difficultiesin previous studies in our group .
- In the case of compounds 5c and 5f, the diastereomeric excesswas measured using the purified diastereomeric mixtures, since impurity signalscomplicated the region of interest when crude material was analyzed .
- Kaye , P. T. and Ravindran , S. S. 1994 . S. Afr. J. Chem. , 47 : 1
- Sykes , P. 1981 . A Guidebookto Mechanism in Organic Chemistry , 5th 237 London : Longman .
- The ester 5e (0.21 g) was added dropwise to conc. H2SO4(0.5 mL), and the resulting mixture was then poured onto ice. Work-up affordedthe crude 3-oxo-2-exo-bornyl 2,3-diphenylpropanoate (9% d.e. as determinedby 1H NMR spectroscopy), which was hydrolyzed bystirring with LiOH.H2O in THF for 3 days at room temperatureto yield 2,3-diphenylpropanoic acid (4% e.e.; as determined by optical rotation);[α]D 27+5.3 (c 1.0in benzene) {lit. (9), [α]D 25+140.8 (c 4.5 in benzene, for the S-enantiomer)} .
- Watson , M. B. and Youngson , G. W. 1968 . J. Chem. Soc. (C). , : 258
- In assigning enolate geometry, the O-metal group is taken tohave a higher priority than the O-alkylgroup. Configurational assignment at the new chiral center will depend, ineach case, on the relative priority of the substituent, R .
- Helmchen , G. , Selim , A. , Dorsch , D. and Taufer , I. 1983 . Tetrahedron Lett. , 24 : 3213
- Evans , M. D. and Kaye , P. T. 1998 . Synth. Commun. , 28 : 4485
- Klein , R. MSc . 1999 . thesis Rhodes University .
- Chemical shift data cited in this format refer to correspondingsignals for the diastereomeric components .
- Work-up and flash chromatography yielded a 1:4 mixture of thestarting material 4a and the diastereomericbenzylated products 5a, which resisted numerousattempts to effect separation .
- Work-up and flash chromatography yielded a 1:2 mixture of thestarting material 4b and the diastereomericbenzylated products 5b, which resisted numerousattempts to effect separation .