L. H. Gade and G. D. Engel
FULL PAPER
methylsuccinate): 7.80 min, tR (dimethyl itaconate): 8.67 min; hydrogena-
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f) S. C. Bourque,H. Alper,L. E. Manzer,P. Arya, J. Am. Chem. Soc.
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tion of Z-a-acetamido cinnamic acid methyl ester: T(injector) 2508C,
À1
T(interface) 2808C,30 m  0.22 mm,0.5 mLmin
He (column flow),
61.0 kPa (column pressure),split 1:70. Temperature program: 130 8C,
0.5 min,10 8CminÀ1,250 8C,3 min. tR (methyl N-acetylphenylalanate):
9.47 min, tR (methyl Z-a-acetamidocinnamate): 11.23 min.
M. Kustos,A.-M. Caminade,J.-P. Majoral,B. Chaudret,
Organo-
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The determination of the enantiomeric excesses of 2-methyl-dimethylsuc-
cinate was effected by gas chromatography with a chiral column (chiraldex
G-Ta, g-cyclodextrin,trifluoroacetyl,20 m  0.25 mm) in a Shimadzu GC-
14A-gas chromatograph with FID detector. Method: T(injector) 2008C,
T(detector) 2008C,split 1:100,140 kPa,He; T(start) 608C,0.8 8CminÀ1
to 788C,5 8CminÀ1 to 1208C,5 min. tR (S enantiomer) 17.4 min, tR (R
enantiomer) 18.4 min.
In the case of methyl N-acetyl phenylalanate,the ee values were
determined by measuring the optical rotation and comparison with the
literature value [a]2D0 101.58 (c 1.0,CHCl 3).[31]
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General procedure for the hydrogenation experiments: The ratio Rh/
substrate was 1:400 in all cases. About 12 mg of the catalyst precursor was
put under an inert-atmosphere. The calculated amount of substrate was
added and the mixture was dissolved in absolute methanol (70 mL). The
clear solution was transferred to a laboratory autoclave (B¸chi mini-clave
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Acknowledgements
We acknowledge support from the Deutsche Forschungsgemeinschaft
(Gerhard Hess Award),the Institut Universitaire de France and the CNRS
(AIP-Program). We thank the Fonds der Chemischen Industrie and the
Studienstiftung des Deutschen Volkes for doctoral fellowships (to G.E.)
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