Practical and Highly Efficient Synthesis of Remdesivir from GS-441524.

A three-step sequence for preparing remdesivir, an important anti-SARS-CoV-2 drug, is described. Employing N , N -dimethylformamide dimethyl acetal (DMF-DMA) as a protecting agent, this synthesis started from (2 R ,3 R ,4 S ,5 R )-2-(4-aminopyrrolo[2,1- f ][1,2,4]triazin-7-yl)-3,4-dihydroxy-5-(hydroxymethyl)tetrahydro-furan-2-carbonitrile (GS-441524) and consisted of three reactions, including protection, phosphoramidation, and deprotection. The advantages of this approach are as follows: (1) the protecting group could be removed under a mild deprotection condition, which avoided the generation of the degraded impurity; (2) high stereoselectivity was achieved in the phosphorylated reaction; (3) this synthesis could be performed successively without purification of intermediates. Moreover, the overall yield of this approach on a gram scale could be up to 85% with an excellent purity of 99.4% analyzed by high-performance liquid chromatography (HPLC).