Discovery of novel spiro 1,3,4-thiadiazolines as potent, orally bioavailable and brain penetrant KSP inhibitors.

Kinesin spindle protein (KSP) is a mitotic kinesin that is expressed only in proliferating cells and plays a key role in spindle pole separation, formation of a bipolar mitotic spindle, as well as centrosome separation and maturation. Inhibition of KSP has the potential to provide anti-tumor activity while avoiding peripheral neuropathy associated with some microtubule-targeted drugs. Based on MK-0731 and related heterocyclic compounds targeting the KSP monastrol binding site, structurally constrained spiro-cyclic KSP inhibitors were designed. In particular, rapid evaluation and optimization of the novel spiro 1,3,4-thiadiazolines resulted in a series of potent KSP inhibitors demonstrating mechanism based activities in cells, including induction of the mitotic marker phospho-histone H3 and induction of monaster spindle formation. Further optimization of the pharmacokinetic (PK) properties afforded MK-8267 as a potent, orally bioavailable and brain penetrant KSP inhibitor which showed anti-tumor activity in preclinical xenograft models.

Scaffold hopping by net photochemical carbon deletion of azaarenes.

Discovery chemists routinely identify purpose-tailored molecules through an iterative structural optimization approach, but the preparation of each successive candidate in a compound series can rarely be conducted in a manner matching their thought process. This is because many of the necessary chemical transformations required to modify compound cores in a straightforward fashion are not applicable in complex contexts. We report a method that addresses one facet of this problem by allowing chemists to hop directly between chemically distinct heteroaromatic scaffolds. Specifically, we show that selective photolysis of quinoline N-oxides with 390-nanometer light followed by acid-promoted rearrangement affords N-acylindoles while showing broad compatibility with medicinally relevant functionality. Applications to late-stage skeletal modification of compounds of pharmaceutical interest and more complex transformations involving serial single-atom changes are demonstrated.

A Metallaphotoredox Method for the Expansion of Benzyl SAR on Electron-Deficient Amines.

A metallaphotoredox reaction is described that allows for the efficient exploration of benzyl structure-activity relationships on electron-deficient amines. Typically, accessing a variety of benzyl groups on these substrates can be difficult due to the limited availability of the prerequisite building blocks, namely benzyl halides. However, the use of aryl bromides in this metallaphotoredox reaction allows for greater diversity in the benzyl piece. The reaction scope is discussed herein, including conditions for product scaleup using flow.

Continuous Flow Enables Metallaphotoredox Catalysis in a Medicinal Chemistry Setting: Accelerated Optimization and Library Execution of a Reductive Coupling between Benzylic Chlorides and Aryl Bromides.

Continuous flow has been used widely in process chemistry and academic settings for various applications. However, initial reaction discovery has generally remained "batch-exclusive" despite the existence of efficient, reproducible flow systems. We hereby disclose a workflow to bridge the gap between early medicinal chemistry efforts and process-scale development, showcased by the discovery and optimization of a metallaphotoredox-catalyzed cross-coupling between benzylic chlorides and aryl bromides, followed by two library syntheses of complex drug-like compounds.