Development of a Large-Scale Cyanation Process Using Continuous Flow Chemistry En Route to the Synthesis of Remdesivir.

The implementation of cyanation chemistry at manufacturing scales using batch equipment can be challenging because of the hazardous nature of the reagents employed and the tight control of reaction parameters, including cryogenic temperatures, that help to afford acceptable selectivity and conversion for the desired reaction. Application of continuous flow chemistry offers a means to mitigate the risk associated with handling large amounts of hazardous reagents and to better control the reaction parameters. A case study describing the cyanation of a glycoside using continuous flow chemistry toward the synthesis of the drug candidate remdesivir is presented.

Photochemical generation of 9H-fluorenyl radicals.

A series of 9-substituted fluorenols and 9,9'-disubstituted-9,9'-bifluorenyls were irradiated to give products derived from fluorenyl radicals. Product distribution was solvent dependent. A TEMPO adduct was isolated from the photoexcitation of 9-fluorenol.

Palladium-catalyzed selective carboelimination and cross-coupling reactions of benzocyclobutenols with aryl bromides.

The palladium-catalyzed selective β-carboelimination and cross-coupling chemistry of benzocyclobutenols is described. In contrast to the base-mediated ring-opening reactions of benzocyclobutenols, this variant proceeds with exclusive cleavage of the proximal bond.

Synthesis of benzodiquinanes via tandem palladium-catalyzed semipinacol rearrangement and direct arylation.

A palladium-catalyzed tandem semipinacol rearrangement/direct arylation reaction using α-aryl isopropenyl-tert-cyclobutanols has been developed. This reaction gives access to benzodiquinanes in moderate to good yields and tolerates alkyl-, alkoxy-, and halogen-substituted aryl groups.