Discovery of (4-Pyrazolyl)-2-aminopyrimidines as Potent and Selective Inhibitors of Cyclin-Dependent Kinase 2

CDK2 is a critical regulator of the cell cycle. For a variety of human cancers, the dysregulation of CDK2/cyclin E1 can lead to tumor growth and proliferation. Historically, early efforts to develop CDK2 inhibitors with clinical applications proved unsuccessful due to challenges in achieving selectivity over off-target CDK isoforms with associated toxicity. In this report, we describe the discovery of (4-pyrazolyl)-2-aminopyrimidines as a potent class of CDK2 inhibitors that display selectivity over CDKs 1, 4, 6, 7, and 9. SAR studies led to the identification of compound 17, a kinase selective and highly potent CDK2 inhibitor (IC50 = 0.29 nM). The evaluation of 17 in CCNE1-amplified mouse models shows the pharmacodynamic inhibition of CDK2, measured by reduced Rb phosphorylation, and antitumor activity.

Discovery of Pyrazolopyridine Derivatives as HPK1 Inhibitors

In spite of the great success of immune checkpoint inhibitors in immune-oncology therapy, an urgent need still exists to identify alternative approaches to broaden the scope of therapeutic coverage. Hematopoietic progenitor kinase 1 (HPK1), also known as MAP4K1, functions as a negative regulator of activation signals generated by the T cell antigen receptor. Herein we report the discovery of novel pyrazolopyridine derivatives as selective inhibitors of HPK1. The structure-activity relationship campaign led to the discovery of compound 16, which has shown promising enzymatic and cellular potency with encouraging kinome selectivity. The outstanding pharmacokinetic profiles of 16 in rats and monkeys supported further evaluations of its efficacy and safety in preclinical models.

Potent and Selective Biaryl Amide Inhibitors of Hematopoietic Progenitor Kinase 1 (HPK1)

Herein we report the discovery of a novel biaryl amide series as selective inhibitors of hematopoietic protein kinase 1 (HPK1). Structure-activity relationship development, aided by molecular modeling, identified indazole 5b as a core for further exploration because of its outstanding enzymatic and cellular potency coupled with encouraging kinome selectivity. Late-stage manipulation of the right-hand aryl and amine moieties surmounted issues of selectivity over TRKA, MAP4K2, and STK4 as well as generating compounds with balanced in vitro ADME profiles and promising pharmacokinetics.

Convergent Synthesis of α-Branched Amines by Transition-Metal-Catalyzed C-H Bond Additions to Imines

α-Branched amines are ubiquitous in drugs and natural products, and consequently, synthetic methods that provide convergent and efficient entry to these structures are of considerable value. Transition-metal-catalyzed C-H bond additions to imines have the potential to be highly practical and atom-economic approaches for the synthesis of a diverse and complex array of α-branched amine products. These strategies typically employ readily available starting inputs, display high functional group compatibility, and often avoid the production of stoichiometric waste byproducts. A number of C-H functionalization methods have also been developed that incorporate cascade cyclization pathways to give amine-substituted carbocycles, and in many cases, proceed with the formation of multiple stereogenic centers. Advances in the area of asymmetric C-H bond additions to imines have also been achieved through the use of chiral imine N-substituents as well as by enantioselective catalysis.

Transition-Metal-Catalyzed C-H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

The transition-metal-catalyzed addition of C-H bonds to carbonyls, imines, and related polarized π bonds has emerged as a particularly efficient and powerful approach for the construction of an incredibly diverse array of heteroatom-substituted products. Readily available and stable inputs are typically employed, and reactions often proceed with very high functional group compatibility and without the production of waste byproducts. Additionally, many transition-metal-catalyzed C-H bond additions to polarized π bonds occur within cascade reaction sequences to provide rapid access to a diverse array of different heterocyclic as well as carbocyclic products. This review highlights the diversity of transformations that have been achieved, catalysts that have been used, and types of products that have been prepared through the transition-metal-catalyzed addition of C-H bonds to carbonyls, imines, and related polarized π bonds.

Highly Stereoselective Cobalt(III)-Catalyzed Three-Component C-H Bond Addition Cascade

A highly stereoselective three-component C(sp(2) )-H bond addition across alkene and polarized π-bonds is reported for which Co(III) catalysis was shown to be much more effective than Rh(III) . The reaction proceeds at ambient temperature with both aryl and alkyl enones employed as efficient coupling partners. Moreover, the reaction exhibits extremely broad scope with respect to the aldehyde input; electron rich and poor aromatic, alkenyl, and branched and unbranched alkyl aldehydes all couple in good yield and with high diastereoselectivity. Multiple directing groups participate in this transformation, including pyrazole, pyridine, and imine functional groups. Both aromatic and alkenyl C(sp(2) )-H bonds undergo the three-component addition cascade, and the alkenyl addition product can readily be converted into diastereomerically pure five-membered lactones. Additionally, the first asymmetric reactions with Co(III) -catalyzed C-H functionalization are demonstrated with three-component C-H bond addition cascades employing N-tert-butanesulfinyl imines. These examples represent the first transition metal catalyzed C-H bond additions to N-tert-butanesulfinyl imines, which are versatile and extensively used intermediates for the asymmetric synthesis of amines.

Preparation of Enantiomerically Pure Perfluorobutanesulfinamide and Its Application to the Asymmetric Synthesis of α-Amino Acids

A high yielding and practical two-step synthesis of enantiomerically pure perfluorobutanesulfinamide from Senanayake's 2-aminoindanol-derived sulfinyl transfer reagent was developed and carried out on a multigram scale. Straightforward condensation of this sulfinamide with ethyl glyoxylate provided the N-perfluorobutanesulfinyl imino ester. The utility of this activated N-sulfinyl imino ester was demonstrated for reactions that gave either no product or very low yields with the corresponding less electrophilic N-tert-butanesulfinyl derivative. Specifically, the Rh(III)-catalyzed C-H bond addition of aromatic compounds to the N-perfluorobutanesulfinyl imino ester provided arylglycines with very high diastereoselectivities for a range of directing groups including pyrrolidine amide, azo, sulfoximine, 1-pyrazole, and 1,2,3-triazole functionalities. Thermal asymmetric aza-Diels-Alder reactions also proceeded in good yields and with high selectivity, including for the substituted dienes (E)-1,3-pentadiene and (2E,4E)-2,4-hexadiene.

Cobalt(III)-Catalyzed C-H Bond Amidation with Isocyanates

The first examples of cobalt(III)-catalyzed C-H bond addition to isocyanates are described, providing a convergent strategy for arene and heteroarene amidation. Using a robust air- and moisture-stable catalyst, this transformation demonstrates a broad isocyanate scope and good functional-group compatibility and has been performed on gram scale.

Facile synthesis of unsymmetrical acridines and phenazines by a Rh(III)-catalyzed amination/cyclization/aromatization cascade

We report formal [3 + 3] annulations of aromatic azides with aromatic imines and azobenzenes to give acridines and phenazines, respectively. These transformations proceed through a cascade process of Rh(III)-catalyzed amination followed by intramolecular electrophilic aromatic substitution and aromatization. Acridines can be directly prepared from aromatic aldehydes by in situ imine formation using catalytic benzylamine.

Enantioselective synthesis of cocaine C-1 analogues using sulfinimines (N-sulfinyl imines)

The first examples of cocaine analogues having substituents (methyl, ethyl, n-propyl, n-pentyl, and phenyl) at the C-1 position of the cocaine tropane skeleton were prepared by heating sulfinimine-derived α,β-unsaturated pyrrolidine nitrones. In the presence of the Lewis acid Al(O(t)Bu)(3) the nitrones undergo an intramolecular [3 + 2] cycloaddition to give tricyclic isoxazolidines that were transformed in three steps to the cocaine analogues. In the absence of the Lewis acid, lactams were formed resulting from rearrangement of the nitrone to an oxaziridine. A novel Pd- and base-promoted rearrangement of methanesulfonate salts of isoxazolidine to bridge bicyclic[4.2.1]isoxazolidines was discovered.

The managed care contract: the blueprint for monitoring agreements

Healthcare providers generally undertake monitoring programs of managed care arrangements as a way of analyzing financial performance, uncovering lapses in contractually mandated performance that might expose the organization to financial loss, and gathering information that can be helpful in renegotiating the contract or negotiating new arrangements. To secure access to the information needed to achieve these goals, the provider should ensure that the contract spells out the information required, the health plan's obligations to supply this information, and the consequences of the plan's failure to meet those obligations. Such consequences may include financial penalties for the plan and special termination rights for the provider. Without a contractually explicit assurance that the needed information will be available, a provider may find itself with no way to achieve its contract-monitoring goals.

Risk pools: payers and providers take the plunge

Providers considering managed care risk pool arrangements should understand thoroughly what services the pool covers, the time period covered, and how the pool is administered. Important issues related to pool administration include how credits and debits are applied; when the accounting occurs (interim, year-end, or contract termination); and provisions for reports, audit rights, and dispute resolution. Although a pool arrangement gives the health plan control over claims payment, the risk allocation made possible through a pool arrangement helps ensure that the economic incentives of the health plan and the provider are aligned.