Sustainability by design: automated nanoscale 2,3,4-trisubstituted quinazoline diversity

Small molecule synthesis is equally important for materials and pharmaceuticals. However, the traditional approach performed in pharmaceutical R&D including maintenance of million-sized libraries and optimization synthesis of hundreds or even thousands of chemicals on a mmol or larger scale lacks sustainability. Here, we exemplify the synthetic execution of a newly designed quinoxaline reaction towards a transformative sustainability in chemistry. This includes nanoscale synthesis, deep chemical space exploration, scalability over 6 orders of magnitude from milligram up to 10-gram resynthesis of quinazolines enabled by the simultaneous variation of four classes of building blocks. Benefits of our approach include a simple to perform, one-step procedure, mild reaction conditions and access to a very large chemical space through accessing many available building blocks. More than thousand derivatives were produced in an automated fashion on a nanoscale using positive pressure facilitated dispensing. Along with these advantages, there is a considerable reduction in synthetic effort, reagents, solvent, glass and plastic consumables and power consumption to decrease the footprint of synthetic chemistry.