The direct cyanomethylation of indoles at the 2- or 3-position was achieved via photoredox catalysis. The versatile nitrile synthon is introduced as a radical generated from bromoacetonitrile, a photocatalyst, and blue LED as a light source. The mechanism of the reaction is explored by determination of the Stern-Volmer quenching constants. By combining photophysical data and mass spectrometry to follow the catalyst decomposition, the catalyst ligands were tuned to enable synthetically useful yields of radical coupling products. A range of indole substrates with alkyl, aryl, halogen, ester, and ether functional groups participate in the reaction, affording products in 16-90% yields. The reaction allows the rapid construction of synthetically useful cyanomethylindoles, products that otherwise require several synthetic steps.

Tau prions feature in the brains of patients suffering from Alzheimer's disease and other tauopathies. For the development of therapeutics that target the replication of tau prions, a high-content, fluorescence-based cell assay was developed. Using this high-content phenotypic screen for nascent tau prion formation, a 4-piperazine isoquinoline compound (1) was identified as a hit with an EC 50 value of 390 nM and 0.04 K p,uu . Analogs were synthesized using a hypothesis-based approach to improve potency and in vivo brain penetration resulting in compound 25 (EC 50 = 15 nM; K p,uu = 0.63). We investigated the mechanism of action of this series and found that a small set of active compounds were also CDK8 inhibitors.