Synthesis of (2R,4S)-4-Amino-5-hydroxybicyclo[3.1.1]heptane-2-carboxylic Acid via an Asymmetric Intramolecular Mannich Reaction.

Inhibition of human ornithine aminotransferase interferes with glutamine and proline metabolism in hepatocellular carcinoma, depriving tumors of essential nutrients. A proposed mechanism-based inhibitor containing a bicyclo[3.1.1]heptanol warhead is reported herein. The proposed inactivation mechanism involves a novel α-iminol rearrangement. The synthesis of the proposed inhibitor features an asymmetric intramolecular Mannich reaction, utilizing a chiral sulfinamide. This study presents a novel approach toward the synthesis of functionalized bicyclo[3.1.1]heptanes and highlights an underutilized method to access enantiopure exocyclic amines.

Design, development, synthesis, and crystal structure of the prototype of a new class of deep blue-fluorescing boron heterocycle estrogen mimics.

To further the development of boron heterocyclic compounds that are useful to medicinal chemistry, we demonstrate how the class of compounds known as the diazaborines can be elaborated to produce an exceptionally close structural mimic of a natural estrogen. After building progressively closer models, a benzyloxy-substituted formylphenylboronic acid was ultimately condensed with a hydroxymethylated ß-hydrazinocyclopentenone to give, after debenzylation, an isosteric mimic (diazaborine 1) of the naturally-occurring estrogen equilenin and the prototype of a new class of boron heterocycle estrogen mimics. X-ray crystallography revealed the prototype to be planar, with a transmolecular interoxygen distance virtually identical to that found in equilenin and with a strong hydrogen-bond-donating hydroxyl group. From this it can be anticipated that members of this unique class of boron heterocycle estrogen mimics will be found to possess useful biological properties. Furthermore, the prototype was found to fluoresce in the deep blue region of the visible spectrum, and so the development of members serving as light-emitting probes in biochemical and biological studies can also be anticipated.

Potent GCN2 Inhibitor Capable of Reversing MDSC-Driven T Cell Suppression Demonstrates In Vivo Efficacy as a Single Agent and in Combination with Anti-Angiogenesis Therapy.

General control nonderepressible 2 (GCN2) protein kinase is a cellular stress sensor within the tumor microenvironment (TME), whose signaling cascade has been proposed to contribute to immune escape in tumors. Herein, we report the discovery of cell-potent GCN2 inhibitors with excellent selectivity against its closely related Integrated Stress Response (ISR) family members heme-regulated inhibitor kinase (HRI), protein kinase R (PKR), and (PKR)-like endoplasmic reticulum kinase (PERK), as well as good kinome-wide selectivity and favorable PK. In mice, compound 39 engages GCN2 at levels ≥80% with an oral dose of 15 mg/kg BID. We also demonstrate the ability of compound 39 to alleviate MDSC-related T cell suppression and restore T cell proliferation, similar to the effect seen in MDSCs from GCN2 knockout mice. In the LL2 syngeneic mouse model, compound 39 demonstrates significant tumor growth inhibition (TGI) as a single agent. Furthermore, TGI mediated by anti-VEGFR was enhanced by treatment with compound 39 demonstrating the complementarity of these two mechanisms.