[Figure 6]
After the filtration of the cation exchange resin beads, the desorption
was carried out using a mixture of 5% NaOH and cyclopentyl methyl ether
(CPME) in a volumetric ratio of 1:1. After the phase separation the
product amine was oiled out from the ether phase as the hydrochloride
salt using gaseous HCl. Herein, CPME offers a relatively low water
content with the organic layer, which is highly important to precipitate
the hydrochloride-salt of the amine. After evaporating the residual
CPME, ca. 1 g of a brown-orange oil was obtained with a purity of
>99% (see Figure S 7 to Figure S 10 for further
information). Any further purification steps, e.g. by column
chromatography or recrystallization, were not required highlighting the
applicability of this method.