Stearoyl serine methyl ester

Figure 10 Images of domains of monolayers of the o-enantiomer, L-enantiomo-, and racemic mixture of A-stearoylserine methyl ester clearing showing chiral discrimination effects. The domains of the enantiomers display unique curvature, and the domain of the racemic mixture shows featnres with both senses of curvature and hence evidence for chiral segregation. Reproduced from Ref. 62. American Chemical Society, 2003, and the figure caption reads as follows Chiral discrimination of the condensed-phase domains of N-stearoyl serine methyl ester monolayers spread on pH 3 water, (a) D-enantiomer (b) L-enantiomer (c) and (d) 1 1 dl racemate. Image size 80 x 80 pm.

Stearoyl chloride in dimethylformamide added to DL-serine methyl ester (prepared from the hydrochloride with a soln. of the stoichiometric amount of Na in methanol) in dimethylformamide containing pyridine, and allowed to stand 1 hr. at room temp. N-stearoyl-DL-serine methyl ester. Y 70%. F. e. s. B. Weiss, J. Org. Ghem. 24, 1367 (1959). 

Ai-Stearoylamino acids and their methyl esters were synthesized from enantiomeric and racemic forms of tyrosine, serine, alanine, and tryptophan (Fig. 16). Analogs of these molecules were investigated initially over 30 years ago by Zeelen and Havinga, who found stereochemical differentiation in the monolayer HjA isotherms of these materials (Zeelen, 1956 Zeelen and Havinga, 1958). We have extended this study using more sensitive Langmuir balances, a wider array of dynamic and equilibrium techniques, and the A-stearoyl methyl esters of the amino acids (Harvey et al., 1989 Harvey and Arnett, 1989). 

Figure 17 shows the 11/A isotherms of racemic and enantiomeric films of the methyl esters of 7V-stearoyl-serine, -alanine, -tryptophan, and -tyrosine on clean water at 25°C. Although there appears to be little difference between the racemic and enantiomeric forms of the alanine surfactants, the N-stearoyl-tyrosine, -serine, and -tryptophan surfactants show clear enantiomeric discrimination in their WjA curves. This chiral molecular recognition is first evidenced in the lift-off areas of the curves for the racemic versus enantiomeric forms of the films (Table 2). As discussed previously, the lift-off area is the average molecular area at which a surface pressure above 0.1 dyn cm -1 is first registered. The packing order differences in these films, and hence their stereochemical differentiation, are apparently maintained throughout the compression/expansion cycles. 

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