Lang et al. (1999) also amidated sophorolipids, but they used lactonic-SL as feed-
stock. Depending on theN-alkylation grade of the amine (branched alkyl chain,
dialkylation), the reaction had to be performed differently. In the case of primary
N-alkylated amines only catalytic amounts of ammonium chloride were necessary
for successful conversions. The longer the alkyl chain, the faster was the reaction.
The formation of theN,N-diethyl amide was only possible if diethyl amine was
predeprotonized withn-butyl lithium.
17.4.2 Enzymatically modified sophorolipids, enzymatically
modified
Thus, to date, physiological variables during fermentations have provided routes to
the variation of sophorolipid composition, but have not led to well-defined pure
compounds. An alternative strategy to the tailoring of sophorolipid structure during
thein vivoprocessing step is to develop methods for the regioselective modification
of sophorolipids after microbial formation.
382 17 Enzymatic Synthesis and Modification of Glycolipids
Figure 7. Conversion of mono- or diacetylated 17-L-([2’-O-b-D-glucopyranosyl-b-D-glucopyrano-
syl]-oxy)-octadecanoic acid into acid amides by the reaction with amine compounds in a methylene
chloride solvent in the presence ofN-methyl-2-chloro-pyridinium iodide and tributylamine (Ishigami,
1994).