Discovery of novel triazolobenzazepinones as γ-secretase modulators with central Aβ42 lowering in rodents and rhesus monkeys

Chemoselective Ru-Catalyzed Oxidative Lactamization vs Hydroamination of Alkynylamines: Insights from Experimental and Density Functional Theory Studies

The Ru-catalyzed intramolecular oxidative amidation (lactamization) of aromatic alkynylamines with 4-picoline N-oxide as an external oxidant has been developed. This chemoselective process is very efficient to achieve medium-sized ε- and ζ-lactams (seven- and eight-membered rings) but not for the formation of common δ-lactams (six-membered rings). DFT studies unveiled the capital role of the chain length between the amine and the alkyne functionalities: the longer the connector, the more favored the lactamization process vs hydroamination.

Oxidation of Nonactivated Anilines to Generate N-Aryl Nitrenoids

A low-temperature, protecting-group-free oxidation of 2-substituted anilines has been developed to generate an electrophilic N-aryl nitrenoid intermediate that can engage in C-NAr bond formation to construct functionalized N-heterocycles. The exposure of 2-substituted anilines to PIFA and trifluoroacetic acid or 10 mol % Sc(OTf)₃ triggers nitrenoid formation, followed by productive and selective C-NAr and C-C bond formation to yield spirocyclic- or bicyclic 3H-indoles or benzazepinones. Our experiments demonstrate the breadth of these oxidative processes, uncover underlying fundamental elements that control selectivity, and demonstrate how the distinct reactivity patterns embedded in N-aryl nitrenoid reactive intermediates can enable access to functionalized 3H-indoles or benzazepinones.

Enantioselective Synthesis of Medium-Sized Lactams via Chiral α,β-Unsaturated Acylammonium Salts

Medium-sized lactams are important structural motifs found in a variety of bioactive compounds and natural products but are challenging to prepare, especially in optically active form. A Michael addition/proton transfer/lactamization organocascade process is described that delivers medium-sized lactams, including azepanones, benzazepinones, azocanones, and benzazocinones, in high enantiopurity through the intermediacy of chiral α,β-unsaturated acylammonium salts. An unexpected indoline synthesis was also uncovered, and the benzazocinone skeleton was transformed into other complex heterocyclic derivatives, including spiroglutarimides, isoquinolinones, and δ-lactones.

Gamma Secretase Modulators: New Alzheimer's Drugs on the Horizon?

The rapidly aging population desperately requires new therapies for Alzheimer's disease. Despite years of pharmaceutical research, limited clinical success has been realized, with several failed disease modification therapies in recent years. On the basis of compelling genetic evidence, the pharmaceutical industry has put a large emphasis on brain beta amyloid (Aβ) either through its removal via antibodies or by targeting the proteases responsible for its production. In this Perspective, we focus on the development of small molecules that improve the activity of one such protease, gamma secretase, through an allosteric binding site to preferentially increase the concentration of the shorter non-amyloidogenic Aβ species. After a few early failures due to poor drug-like properties, the industry is now on the cusp of delivering gamma secretase modulators for clinical proof-of-mechanism studies that combine potency and efficacy with improved drug-like properties such as lower cLogP, high central nervous system multiparameter optimization scores, and high sp(3) character.