Authors:Han Yueh, Anastasia Voevodin and Aaron B. Beeler
9-Hydroxymethylxanthene derivatives were optimized as a photolabile protecting group for amines in flow chemistry. 9-Methylxanthene and 2-methoxy-9-methylxanthene showed excellent deprotection yields in protic and aprotic solvents, respectively. The protecting group has good stability in acidic, basic, and thermal conditions and was successfully utilized for protection and deprotection of a variety of amines. A multistep continuous-flow synthesis of a piperazinylcarbonyl-piperidine derivative utilized the 2-methoxy-9-methylxanthene as the key protecting group utilized in an orthogonal manner.
There are great opportunities for innovation in the drug discovery process, particularly in the lead development phase. The traditional “design–synthesize–screen” cycle has seen little innovation as a whole despite major advances at each stage, including automated purification and synthesis as well as high throughput biological screening. It could be argued that the hit-to-lead and lead optimization processes remain slow and modular with inefficient flow of information, resulting in a loss of time and money. New flow technologies may provide a promising foundation for developing a continuous integrated small molecule optimization platform that would greatly enhance hit-to-lead and lead optimization programs. Herein, we discuss major developments in integrating synthesis, purification, screening, and machine learning into a single continuous-flow platform and provide some insight into future directions of this field.
Authors:Ketan Pimparkar, Bernard Yen, John R. Goodell, Veronique I. Martin, Wen-Hsuan Lee, John A. Porco Jr., Aaron B. Beeler and Klavs F. Jensen
In an effort to utilize microfluidics to enable photochemistry, we have devised a method for fabrication of devices with UV-transmissive glass. The photochemical device is successfully incorporated into a system utilizing high-pressure capillary mercury lamps and cooling system. We have demonstrated the ability to carry out photochemical transformations with substantial rate acceleration. Furthermore, we highlight the ability to carry out analytical-scale reactions on a pulse flow automated system while modulating wavelength and residence time to identify optimal photochemical reaction conditions. The analytical conditions were also successfully converted to continuous-flow preparative scale.