Abstract: A method for catalytic asymmetric synthesis of a phosphorus-stereogenic (P-stereogenic) nucleoside derivative of formula (3) and a catalyst used therein. The P-stereogenic nucleoside derivative (3) can be hydrolyzed to obtain remdesivir.

Abstract: A polymyxin B component or salts thereof, and a preparation and application thereof. The polymyxin B component includes six ?,?-diaminobutyric acids respectively at positions 1, 3-5 and 8-9, two threonine residues at positions 2 and 10, a phenylalanine residue at position 6 and a leucine residue at position 7 linked in sequence. The threonine residue at position 10 is linked to the ?,?-diaminobutyric acid at position 4 by an amido bond, and the ?,?-diaminobutyric acid at position 1 is linked to 6-methyloctyl-2-enoyl.

Abstract: Disclosed are a crystallization water-free calcium dibutyryladenosine cyclophosphate crystal form, and a preparation method and a use thereof. In an X-ray powder diffraction pattern using Cu-K? as a source of radiation, the crystallization water-free calcium dibutyryladenosine cyclophosphate crystal form has characteristic peaks at positions where diffraction angles 2? are equal to 12.3°±0.2°, 17.6°±0.2°, 21.4°±0.2°, 24.7°±0.2°, 25.3°±0.2° and 27.8°±0.2°. The crystallization water-free calcium dibutyryladenosine cyclophosphate crystal form of the present invention has a high purity, and good stability; the preparation method is simple and convenient, has good reproducibility, and is easy to industrially popularize and apply.