An Ozonolysis−Reduction Sequence for the Synthesis of Pharmaceutical Intermediates in Microstructured Devices

The advantages of microstructured reactors were utilized in a two-step process for the preparation of intermediates of vitamin D analogues, which are known to be important compounds in bone and mineral metabolism. The reaction sequence consisting of an ozonolysis step of a double bond and a subsequent reduction was successfully performed in a microplant. Concerning the feasibility and optimization of the two reaction steps in different microreactors, ozonolysis and reduction have initially been investigated separately. A miniaturized ATR sensor was employed for online monitoring of the ozonolysis step. The overall process was then performed in a continuous manner. The utilization of microstructured devices allows for the realization of a safe and highly controlled multistep process with online analysis via FTIR.