A Continuous Flow Process Using a Sequence of Microreactors with In-line IR Analysis for the Preparation of N,N-Diethyl-4-(3-fluorophenylpiperidin-4-ylidenemethyl)benzamide as a Potent and Highly Selective δ-Opioid Receptor Agonist

This article describes the design, optimisation and development of a continuous flow synthesis of N,N-diethyl-4-(3-fluorophenylpiperidin-4-ylidenemethyl)benzamide, a potent delta-opioid receptor agonist developed by AstraZeneca. The process employs a sequence of flow-based microreactors, with integrated purification employing solid-supported reagents and in-line IR analytical protocols using a newly developed ReactIR flow cell. With this monitoring device, initiation of the fourth input flow stream can be precisely controlled during the synthesis.