Construction of N-Boc-2-Alkylaminoquinazolin-4(3H)-Ones via a Three-Component, One-Pot Protocol Mediated by Copper(II) Chloride that Spares Enantiomeric Purity

Efficacy of a brain-penetrant antiviral in lethal Venezuelan and eastern equine encephalitis mouse models

Venezuelan and eastern equine encephalitis viruses (VEEV and EEEV, respectively) are mosquito-borne, neuroinvasive human pathogens for which no FDA-approved therapeutic exists. Besides the biothreat posed by these viruses when aerosolized, arthropod transmission presents serious health risks to humans, as demonstrated by the 2019 outbreak of EEE disease in the United States that resulted in 38 confirmed cases, 19 deaths, and neurological effects in survivors. Here, we describe the discovery of a 2-pyrrolidinoquinazolinone scaffold, efficiently synthesized in two to five steps, whose structural optimization resulted in profound antiviral activity. The lead quinazolinone, BDGR-49, potently reduced cellular VEEV and EEEV titers by >7 log at 1 μM and exhibited suitable intravenous and oral pharmacokinetic profiles in BALB/c mice to achieve excellent brain exposure. Outstanding in vivo efficacy was observed in several lethal, subcutaneous infection mouse models using an 8-day dosing regimen. Prophylactically administered BDGR-49 at 25 mg kg^-1 per day fully protected against a 10× LD₅₀ VEEV Trinidad donkey (TrD) challenge in BALB/c mice. Similarly, we observed 70% protection when 10× LD₅₀ EEEV FL93-939-infected C57BL/6 mice were treated prophylactically with BDGR-49 at 50 mg kg^-1 per day. Last, we observed 100% therapeutic efficacy when mice, challenged with 10× LD₅₀ VEEV TrD, were dosed at 48 hours after infection with BDGR-49 at 25 mg kg^-1 per day. Mouse brain viral titers at 96 hours after infection were reduced to values near the limit of detection. Collectively, these results underscore the substantial development potential of a well-tolerated, brain-penetrant lead compound that shows promise in preventing and treating encephalitic alphavirus disease.

Dihydropyrazinoquinazolinones via SN2 Sulfamidate Ring-Opening and a Sequential Quinazolinone-Amidine Rearrangement Strategy (SQuAReS)

A synthesis of dihydropyrazino-[2,1-b]-quinazolinones is described using a 2-alkylaminoquinazolinone-mediated ring opening of a-/chiral sulfamidates, followed by a tandem quinazolinone-amidine rearrangement termed SQuAReS. This approach takes advantage of sulfamidates whose regioselective ring opening, after hydrolysis, appends an optimally distanced nucleophilic amine to a quinazolinone such that subsequent domino rearrangements are favored, integrating unique substitution patterns on a privileged core. This three-step protocol integrated five telescoped transformations and generated 20 pyrazinoquinazolinones in up to 74% yield with high enantiomeric fidelity and diastereoselectivity.

Piperazinobenzodiazepinones: New Encephalitic Alphavirus Inhibitors via Ring Expansion of 2-Dichloromethylquinazolinones

Venezuelan and eastern equine encephalitis viruses are disease-causing, neuropathic pathogens with no approved treatment options in humans. While expanding the pharmacophoric model of antialphaviral amidines prepared via a quinazolinone rearrangement, we discovered that diamine-treated, 2-dihalomethylquinolinones unexpectedly afforded ring-expanded piperazine-fused benzodiazepinones. Notably, this new chemotype (19 examples) showed potent, submicromolar inhibition of virus-induced cell death, >7-log reduction of viral yield, and tractable structure–activity relationships across both viruses. Antiviral activity was confirmed in primary human neuronal cells. A mechanistic rationale for product formation is proposed, and key structural elements were comparatively modeled between a similarly substituted antiviral amidine and piperazinobenzodiazepinone prototypes to guide future antiviral development.

Diastereoselective, Multicomponent Synthesis of Pyrrolopyrazinoquinazolinones via a Tandem Quinazolinone Rearrangement/Intramolecular Ring Closure of Tautomeric (Z)-Benzamidines

An expedient route to enantiopure, diastereomeric pyrrolopyrazinoquinazolinones was developed following the discovery of a domino quinazolinone rearrangement-intramolecular cyclization of N-H benzamidines. A Ugi-Mumm-Staudinger sequence employing an optically pure proline derivative gave quinazolinones that, upon N-Boc deprotection, rearranged to tautomeric Z-benzamidines. Subsequent spontaneous cyclization afforded 15 diastereomeric pyrazinoquinazolinone pairs in up to 83% overall yield and 89:11 d.r which were separated easily via routine chromatographic purification-the only one required in the entire process.