Synthesis of Akt Inhibitor Ipatasertib. Part 1. Route Scouting and Early Process Development of a Challenging Cyclopentylpyrimidine Intermediate

Herein, the route scouting and early process development of a key cyclopentylpyrimidine ketone intermediate toward the synthesis of Akt inhibitor Ipatasertib are described. Initial supplies of the intermediate were prepared through a method that commenced with the natural product (<i>R</i>)-(+)-pulegone and relied on the early construction of a methyl-substituted cyclopentyl ring system. The first process chemistry route, detailed herein, enabled the synthesis of the ketone on a hundred-gram scale, but it was not feasible for the requisite production of multikilogram quantities of this compound and necessitated the exploration of alternative strategies. Several new synthetic approaches were investigated towards the preparation of the cyclopentylpyrimidine ketone, in either racemic or chiral form, which resulted in the discovery of a more practical route that hinged on the initial preparation of a highly substituted dihydroxypyrimidine compound. The cyclopentane ring in the target was then constructed through a key carbonylative esterification and subsequent tandem Dieckmann cyclization–decarboxylation sequence that was demonstrated in a racemic synthesis. This proof-of-concept was later developed into an asymmetric synthesis of the cyclopentylpyrimidine ketone, which will be described in a subsequent paper, along with the synthesis of Ipatasertib

Spirocyclic β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors: From hit to lowering of cerebrospinal fluid (CSF) amyloid β in a higher species

A hallmark of Alzheimer\u27s disease is the brain deposition of amyloid beta (Aβ), a peptide of 36-43 amino acids that is likely a primary driver of neurodegeneration. Aβ is produced by the sequential cleavage of APP by BACE1 and γ-secretase; therefore, inhibition of BACE1 represents an attractive therapeutic target to slow or prevent Alzheimer\u27s disease. Herein we describe BACE1 inhibitors with limited molecular flexibility and molecular weight that decrease CSF Aβ in vivo, despite efflux. Starting with spirocycle 1a, we explore structure-activity relationships of core changes, P3 moieties, and Asp binding functional groups in order to optimize BACE1 affinity, cathepsin D selectivity, and blood-brain barrier (BBB) penetration. Using wild type guinea pig and rat, we demonstrate a PK/PD relationship between free drug concentrations in the brain and CSF Aβ lowering. Optimization of brain exposure led to the discovery of (R)-50 which reduced CSF Aβ in rodents and in monkey. © 2013 American Chemical Society

Discovery of a Novel Class of Imidazo[1,2‑<i>a</i>]Pyridines with Potent PDGFR Activity and Oral Bioavailability

The in silico construction of a PDGFRβ kinase homology model and ensuing medicinal chemistry guided by molecular modeling, led to the identification of potent, small molecule inhibitors of PDGFR. Subsequent exploration of structure–activity relationships (SAR) led to the incorporation of a constrained secondary amine to enhance selectivity. Further refinements led to the integration of a fluorine substituted piperidine, which resulted in significant reduction of P-glycoprotein (Pgp) mediated efflux and improved bioavailability. Compound <b>28</b> displayed oral exposure in rodents and had a pronounced effect in a pharmacokinetic–pharmacodynamic (PKPD) assay

Discovery and Preclinical Pharmacology of a Selective ATP-Competitive Akt Inhibitor (GDC-0068) for the Treatment of Human Tumors

The discovery and optimization of a series of 6,7-dihydro-5<i>H</i>-cyclopenta­[<i>d</i>]­pyrimidine compounds that are ATP-competitive, selective inhibitors of protein kinase B/Akt is reported. The initial design and optimization was guided by the use of X-ray structures of inhibitors in complex with Akt1 and the closely related protein kinase A. The resulting compounds demonstrate potent inhibition of all three Akt isoforms in biochemical assays and poor inhibition of other members of the cAMP-dependent protein kinase/protein kinase G/protein kinase C extended family and block the phosphorylation of multiple downstream targets of Akt in human cancer cell lines. Biological studies with one such compound, <b>28</b> (GDC-0068), demonstrate good oral exposure resulting in dose-dependent pharmacodynamic effects on downstream biomarkers and a robust antitumor response in xenograft models in which the phosphatidylinositol 3-kinase–Akt–mammalian target of rapamycin pathway is activated. <b>28</b> is currently being evaluated in human clinical trials for the treatment of cancer