The Barton reaction using a microreactor and black light.Continuous-flow synthesis of a key steroid intermediate for an endothelin receptor antagonist

摘要

The Barton reaction (nitrite photolysis) of a steroidal substrate 1,to give 2,a key intermediate for the synthesis of an endothelin receptor antagonist,was successfully carried out in a continuous microflow system using a pyrex glass-covered stainless-steel microreactor having a microchannel (Type A:1000 mum width,107 mum depth,2.2 m length).We found that a 15 W black light (peak wavelength:352 nm) as the light source,suffices for the Barton reaction,creating a compact photo-micro reaction system.Multi-gram scale production was attained using two serially connected,multi-lane microreactors (Type B).