An orally available M inhibitor is effective against wild-type SARS-CoV-2 and variants including Omicron.

Emerging SARS-CoV-2 variants continue to cause waves of new infections globally. Developing effective antivirals against SARS-CoV-2 and its variants is an urgent task. The main protease (M) of SARS-CoV-2 is an attractive drug target because of its central role in viral replication and its conservation among variants.

[4 + 2] Annulation Reaction of Generated Azoalkenes with Azlactones: Access to 4,5-Dihydropyridazin-3(2)-Ones.

An unprecedented [4 + 2] annulation reaction between formed azoalkenes and azlactones has been developed. This reaction provides a facile access to an array of 4,5-dihydropyridazin-3(2)-one derivatives, which are very promising in medicinal applications as potential biologically active candidates. Notably, these dihydropyridazinones could also be synthesized a one-pot reaction protocol by using the formed azlactones from -acyl amino acids and generated azoalkenes from α-halogeno hydrazones.

Divergent synthesis of oxindole derivatives via controllable reactions of isatin-derived para-quinone methides with sulfur ylides.

A catalyst-free and controllable reaction of isatin-derived para-quinone methides with sulfur ylides was developed. This protocol enables the divergent synthesis of two different valuable oxindole derivatives with a broad substrate scope and high stereoselectivities (up to >20 : 1 dr and only the (Z)-configuration).

[4 + 1] annulation reaction of cyclic pyridinium ylides with in situ generated azoalkenes for the construction of spirocyclic skeletons.

Two new types of cyclic pyridinium ylides were designed and further used in reactions with azoalkenes to access structurally diverse spirocyclic compounds. A range of spiropyrazoline oxindoles could be smoothly obtained in up to 99% yield via a [4 + 1] annulation process with oxindole 3-pyridinium ylides as C1 synthons. Similarly, a series of spiropyrazoline indanones could be prepared with indanone 2-pyridinium ylides as C1 synthons.