Dialkylaminoacetonitrile Derivatives as Amide Synthons. A One-Pot Preparation of Heteroaryl Amides via a Strategy of Sequential SNAr Substitution and Oxidation

Innovation in the discovery of the HIV-1 attachment inhibitor temsavir and its phosphonooxymethyl prodrug fostemsavir

The discovery and development of fostemsavir (2), the tromethamine salt of the phosphonooxymethyl prodrug of temsavir (1), encountered significant challenges at many points in the preclinical and clinical development program that, in many cases, stimulated the implementation of innovative solutions in order to enable further progression. In the preclinical program, a range of novel chemistry methodologies were developed during the course of the discovery effort that enabled a thorough examination and definition of the HIV-1 attachment inhibitor (AI) pharmacophore. These discoveries helped to address the challenges associated with realizing a molecule with all of the properties necessary to successfully advance through development and this aspect of the program is the major focus of this retrospective. Although challenges and innovation are not unusual in drug discovery and development programs, the HIV-1 AI program is noteworthy not only because of the serial nature of the challenges encountered along the development path, but also because it resulted in a compound that remains the first and only example of a mechanistically novel class of HIV-1 inhibitor that is proving to be very beneficial for controlling virus levels in highly treatment-experienced HIV-1 infected patients.

Desulfonative photoredox alkylation of N-heteroaryl sulfones - an acid-free approach for substituted heteroarene synthesis

Minisci-type alkylation of electron-deficient heteroarenes has been a pivotal technique for medicinal chemists in the synthesis of drug-like molecules. However, such transformations usually require harsh conditions (e.g., strong acids, stoichiometric amount of oxidants, elevated temperatures, etc.). Herein, by utilizing photoredox catalysis, a highly-selective alkylation method using heteroaryl sulfones has been developed that can be carried out under acid-free and redox-neutral conditions. Because of these mild conditions, challenging yet privileged structures, such as monosaccharides and unprotected secondary amines, can be installed.

One-Pot Oxidative Coupling/Decyanation of 6,7-Diphenylindolizine-5-carbonitriles and 2,3-Diphenylquinolizine-4-carbonitriles

The one-pot oxidative coupling/decyanation reactions of 6,7-diphenylindolizine-5-carbonitriles and 2,3-diphenylquinolizine-4-carbonitriles were investigated using aryl-aryl oxidative coupling reagents. The phenanthroindolizidinones and phenanthroquinolizidinones were produced in 52-89% yields under VOF₃/trifluoroacetic acid or [bis(trifluoroacetoxy)iodo]benzene/BF₃-mediated conditions. This represents a mild and efficient approach to construct these types of pentacyclic skeletons from the corresponding cyano group-activated aza-Diels-Alder cycloadducts. A plausible mechanism of the one-pot oxidative coupling/decyanation reaction was proposed.

Palladium-Catalyzed Synthesis of α-Iminonitriles from Aryl Halides via Isocyanide Double Insertion Reaction

An efficient one-pot synthesis of α-iminonitriles from readily available aryl halides via palladium-catalyzed double isocyanide insertion and elimination has been developed, without using various hypertoxic cyanides and excess oxidants. Furthermore, the utility of this reaction was demonstrated by the rapid total synthesis of quinoxaline and the reaction of functional groups exchanged with aryl halides.

Direct amidation of azoles with formamides via metal-free C-H activation in the presence of tert-butyl perbenzoate

A novel and simple method for the direct amidation of azoles with formamides has been developed. The reaction could occur smoothly in the presence of tert-butyl perbenzoate (TBPB) as an oxidant under metal- and base-free conditions. Direct dehydrogenative cross-coupling of formamides and azoles generated the corresponding products in good yields.

Acetonitrile Derivatives as Carbonyl Synthons. One-Pot Preparation of Diheteroaryl Ketones via a Strategy of Sequential SNAr Substitution and Oxidation

The anion of 2-aryl acetonitrile derivatives reacted with a variety of heteroaryl chlorides or bromides in an S(N)Ar manifold to afford intermediate anions which were susceptible to oxidation. The addition of sodium peroxide and aqueous NH(4)OAc solution effected oxidation to afford aryl heteroaryl ketones in good yields. Aryl acetonitrile derivatives are thus umpolung-type synthons of the corresponding aryl carbonyl functionality.