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Glecaprevir was identified as a potent HCV NS3/4A protease inhibitor, and an enabling synthesis was required to support the preclinical evaluation and subsequent Phase I clinical trials. The enabling route to glecaprevir was established through further development of the medicinal chemistry route. The key steps in the synthesis involved a ring-closing metathesis (RCM) reaction to form the 18-membered macrocycle and a challenging fluorination step to form a key amino acid. The enabling route was successfully used to produce 41 kg of glecaprevir, sufficient to support the preclinical evaluation and early clinical development.

The reaction of o-fluorobenzaldehydes and their O-methyloximes with hydrazine has been developed as a new practical synthesis of indazoles. Utilization of the methyloxime derivatives of benzaldehydes (in the form of the major E-isomers) in this condensation effectively eliminated a competitive Wolf-Kishner reduction to fluorotoluenes, which was observed in the direct preparations of indazoles from aldehydes. Reaction of Z-isomers of methyloximes with hydrazine resulted in the formation of 3-aminoindazoles via a benzonitrile intermediate.

Nitro groups on alternate corners of cubane enhance the acidity of cubyl hydrogen (pK a ∼21) and provide sufficient activation for ready anion formation. The sodium salt of 1,3,5,7-tetranitrocubane reacts easily with electrophiles and leads thereby to yet more highly substituted cubanes, like carbomethoxy- and (trimethylsilyl)tetranitrocubane. Anions from these species are also easily formed and are useful for further substitution on the cubane nucleus. Dinitrogen tetraoxide reacts with the anion of tetranitrocubane to give 1,2,3,5,7-pentanitrocubane, the first cubane to contain vicinal nitro groups. The reaction probably involves oxidation of the anion to the corresponding radical. Similarly, the anion of pentanitrocubane is used to prepare 1,2,3,4,5,7-hexanitrocubane, the most highly nitrated cubane made to date. Single-crystal X-ray structural information is given for both penta- and hexanitrocubane.

A general and practical method for the preparation of unsymmetrically substituted ureas has been developed utilizing palladium-catalyzed amidation. Both aryl bromides and chlorides, as well as heteroaryl chlorides, have been coupled to aryl, benzyl, and aliphatic ureas by using a novel nonproprietary bipyrazole ligand (bippyphos).

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ChemInform Abstract The title compounds (VI), (VII) and (IX) are prepared by novel, convenient and effective procedure.

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