A compound of formula (I) and salts and solvates thereof, wherein R.sup.L is a linker for connection to a cell binding agent, which is formula (IIa) wherein Q is a tripeptide residue of formula (A), where x is 1 or 2, —C(═O)-Q.sup.x-NH— is a dipeptide residue; X is: formula (B), where a=0 to 5, b=0 to 16, c=0 or 1, d=0 to 5; and G.sup.L is a linker for connecting to a Ligand Unit.

##STR00001##

The present disclosure provides a method of preparing a compound of Formula I, wherein R.sup.1 is C.sub.1-C.sub.4 alkyl; R.sup.2 is C1-C4 alkyl; and R.sup.3 is selected from the group consisting of C.sub.1-C.sub.6 alkyl, (aryl)alkyl, and (heteroaryl)alkyl in >95% chemical purity and >95% enantiomeric excess.

##STR00001##

Provided are a tripeptide compound, a preparation method therefor, and an application thereof. The structure of the related compound is represented by formula (I). The provided compound has angiotensin converting enzyme inhibiting bioactivity, and the compound and a pharmaceutical composition thereof play a role in preventing and treating hypertension and other cardiocerebral vascular system diseases.

There is provided an α-carbonyl alkenyl ester and a preparation method therefor, and the α-carbonyl alkenyl ester is further used to react with a primary or secondary amine to prepare an amide. The two reactions are combined to develop an amide bond and peptide bond formation method that directly use carboxylic acids and amines as starting materials and allenones as a condensing reagent. The α-carbonyl alkenyl ester corresponding to an α-amino acid serves as a peptide synthesis building block and is used in solid phase peptide synthesis. The method is carried out under mild reaction conditions, simple to operate, and has a high yield. Compared with existing amide bond condensation reagents, the allenones have the advantages of being simple to prepare, having good stability, a low molecular weight, not racemizing when activating α-chiral carboxylic acids, and is a novel amide bond and peptide bond condensing reagent.

The present disclosure provides a method of preparing a compound of Formula I, wherein R.sup.1 is C.sub.1-C.sub.4 alkyl; R.sup.2 is C1-C4 alkyl; and R.sup.3 is selected from the group consisting of C.sub.1-C.sub.6 alkyl, (aryl)alkyl, and (heteroaryl)alkyl in >95% chemical purity and >95% enantiomeric excess. ##STR00001##

The disclosure provides proteasome inhibitors that can be used to halt cell division of rapidly dividing cells by preventing the degradation of cell cycle-regulating proteins, such as cyclins, cyclin-dependent kinase inhibitors, and p53. The proteasome inhibitor compounds can be used to inhibit the proliferation of cancer cells.

Methods of treating aging related skin changes and of increasing skin thickness with topical administration of N-acyldipeptide derivatives are described. Compositions comprising N-acyldipeptide derivatives, are therapeutically effective for increasing skin thickness, and for treating extrinsic and intrinsic aging and aging related skin changes, such as fine lines, wrinkles, photoaging, hyperpigmentation, laxity, age spots, lentigines, mottled skin, and cellulite.

Provided is a method of preparing an N-acetyl dipeptide and an N-acetyl amino acid, the method including producing the N-acetyl dipeptide and the N-acetyl amino acid by reaction of an amino acid with acetic anhydride or acetyl chloride.

The present invention is directed to intermediates and an efficient process for preparing nirmatrelvir (compound of Formula I) and intermediates useful in the preparation of nirmatrelvir.

##STR00001##

Disclosed are a ring-modified proline short peptide compound and the use thereof, and specifically disclosed is a compound represented by formula (X) or a pharmaceutically acceptable salt thereof.

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