ABSTRACT
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 (2R,3R,4S,5R)-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).
ABSTRACT
Currently, remdesivir is the first and only FDA-approved antiviral drug for COVID-19 treatment. Adequate supplies of remdesivir are highly warranted to cope with this global public health crisis. Herein, we report a Weinreb amide approach for preparing the key intermediate of remdesivir in the glycosylation step where overaddition side reactions are eliminated. Starting from 2,3,5-tri-O-benzyl-d-ribonolactone, the preferred route consisting of three sequential steps (Weinreb amidation, O-TMS protection, and Grignard addition) enables a high-yield (65%) synthesis of this intermediate at a kilogram scale. In particular, the undesirable PhMgCl used in previous methods was successfully replaced by MeMgBr. This approach proved to be suitable for the scalable production of the key remdesivir intermediate.