Abstract: A method for preparing a cyclopeptide and a cyclopeptide preparing by the method are disclosed. The method includes the following steps: (a) providing compounds represented by formulas (I-1) and (I-4); (b) performing a reaction between the compounds of formulas (I-1) and (I-4) to obtain a compound represented by formula (I-5); (c) performing a reaction between the compound of formula (I-5) and the compound represented by formula (I-6) to obtain a compound represented by formula (I-7); (d) performing a cyclization reaction of the compound of formula (I-7) with a catalyst of formula (II) and deprotection to obtain a compound represented by formula (III), wherein the compounds of formulas (I-1), (I-4) to (I-7), (III) and the catalyst of formula (II) are as defined in the specification.

Abstract: A method for preparing a cyclopeptide and a cyclopeptide preparing by the method are disclosed. The method includes the following steps: (A) providing compounds represented by the following formulas (I-1) and (I-2): wherein, G, Ra, Rb, Rc, Rd, and Re are defined in the specification; (B) performing a reaction between the compounds of formulas (I-1) and (I-2) to obtain a compound represented by the following formula (I-3): and (C) performing a cyclization reaction of the compound of formula (I-3) with a catalyst of formula (II) and deprotection to obtain a compound represented by the following formula (III): wherein, G?, Q, M, L1, L2, m, y, and z are defined in the specification.

Abstract: A method for preparing a cyclopeptide and a cyclopeptide preparing by the method are disclosed. The method includes the following steps: (A) providing compounds represented by the following formulas (I-1) and (I-2): wherein, G, Ra, Rb, Rc, Rd, and Re are defined in the specification; (B) performing a reaction between the compounds of formulas (I-1) and (I-2) to obtain a compound represented by the following formula (I-3): and (C) performing a cyclization reaction of the compound of formula (I-3) with a catalyst of formula (II) and deprotection to obtain a compound represented by the following formula (III): wherein, G?, Q, M, L1, L2, m, y, and z are defined in the specification.

Abstract: A catalyst for esterification and polyesterification is proposed. The catalyst is an iron acetylacetonate complex having a formula of Fe(RCOCH2COR)3, where R is methyl or a substituent other than methyl. A method for making an esterified product or a polyesterified product by using the iron acetylacetonate complex through esterification and polyesterification is also disclosed so as to improve the existing processes where hydrochloric acid or sulfuric acid used as the catalyst causes yellowed products, danger operation and environmental pollution.