**Dennis Hülsewede 1, Erik Temmel 2, Peter Kumm <sup>1</sup> and Jan von Langermann 1,\***


**(***S***)-1-(3-Methoxyphenyl)ethylamine**

Received: 27 February 2020; Accepted: 23 April 2020; Published: 27 April 2020

**Abstract:** An integrated biocatalysis-crystallization concept was developed for the continuous amine transaminase-catalyzed synthesis of (*S*)-1-(3-methoxyphenyl)ethylamine, which is a valuable intermediate for the synthesis of rivastigmine, a highly potent drug for the treatment of early stage Alzheimer's disease. The three-part vessel system developed for this purpose consists of a membrane reactor for the continuous synthesis of the product amine, a saturator vessel for the continuous supply of the amine donor isopropylammonium and the precipitating reagent 3,3-diphenylpropionate and a crystallizer in which the product amine can continuously precipitate as (*S*)-1-(3-methoxyphenyl)ethylammonium-3,3-diphenylpropionate.

**Keywords:** amine; biocatalysis; enzyme; process intensification; crystallization; enantioselective
