The present disclosure is directed synthetic methods for the preparation of 4-valyloxybutyric acid. The synthetic methods described herein employ a diverse array of protecting group strategies and reaction conditions. Additionally, the present disclosure is directed to compounds useful as synthetic intermediates in the preparation of 4-valyloxybutyric acid.

The present disclosure is directed synthetic methods for the preparation of 4-valyloxybutyric acid. The synthetic methods described herein employ a diverse array of protecting group strategies and reaction conditions. Additionally, the present disclosure is directed to compounds useful as synthetic intermediates in the preparation of 4-valyloxybutyric acid.

The present disclosure is directed synthetic methods for the preparation of 4-valyloxybutyric acid. The synthetic methods described herein employ a diverse array of protecting group strategies and reaction conditions. Additionally, the present disclosure is directed to compounds useful as synthetic intermediates in the preparation of 4-valyloxybutyric acid.

A CyclotheonellazoleA, a synthesis method therefor, and an application method thereof are provided, and a compound with a structure of formula (I) and a pharmaceutically acceptable salt thereof are provided, the structure of formula (I) is as follows:

##STR00001## R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently selected form the group consisting of a hydrogen group (H), an alkyl group with carbon atoms in a range of 1-6, an alkoxy group with carbon atoms in a range of 1-6, a halogen group, a hydroxyl group, an amino group, a nitro group, a cyano group and a sulfydryl group. A CyclotheonellazoleA natural product is successfully synthesized by a classical retrosynthesis analysis, a stereoscopic structure of the CyclotheonellazoleA natural product is confirmed, extremely excellent protease inhibitory activity of the CyclotheonellazoleA natural product is confirmed by combining a protease inhibition activity experiment, and the CyclotheonellazoleA has a strong application prospect in a pharmaceutical industry.

A CyclotheonellazoleA, a synthesis method therefor, and an application method thereof are provided, and a compound with a structure of formula (I) and a pharmaceutically acceptable salt thereof are provided, the structure of formula (I) is as follows:

##STR00001## R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently selected form the group consisting of a hydrogen group (H), an alkyl group with carbon atoms in a range of 1-6, an alkoxy group with carbon atoms in a range of 1-6, a halogen group, a hydroxyl group, an amino group, a nitro group, a cyano group and a sulfydryl group. A CyclotheonellazoleA natural product is successfully synthesized by a classical retrosynthesis analysis, a stereoscopic structure of the CyclotheonellazoleA natural product is confirmed, extremely excellent protease inhibitory activity of the CyclotheonellazoleA natural product is confirmed by combining a protease inhibition activity experiment, and the CyclotheonellazoleA has a strong application prospect in a pharmaceutical industry.

There is disclosed a process for the production of long chain amino acid and long chain dibasic acid, comprising: (1) reacting long chain keto fatty acid with hydroxylamine or subjecting keto fatty acid to an ammoximation reaction to yield an oxime fatty acid; (2) reacting the oxime fatty acid with an alcohol or a primary amine or a secondary amine to prepare an ester or amide; (3) subjecting the oxime fatty acid ester or amide to the Beckmann rearrangement to yield a mixture of two amide fatty acids; (4) hydrolyzing the mixed amide fatty acids to produce long chain amino acid, long chain dibasic acid, short chain alkylamine, and alkanoic acid.

There is disclosed a process for the production of long chain amino acid and long chain dibasic acid, comprising: (1) reacting long chain keto fatty acid with hydroxylamine or subjecting keto fatty acid to an ammoximation reaction to yield an oxime fatty acid; (2) reacting the oxime fatty acid with an alcohol or a primary amine or a secondary amine to prepare an ester or amide; (3) subjecting the oxime fatty acid ester or amide to the Beckmann rearrangement to yield a mixture of two amide fatty acids; (4) hydrolyzing the mixed amide fatty acids to produce long chain amino acid, long chain dibasic acid, short chain alkylamine, and alkanoic acid.

The present invention relates to trisodium diethylenetriamine pentaacetic acid (DTPA) prodrugs, such as, for example, DTPA di-ethyl esters. The invention further relates to compositions comprising DTPA prodrugs and methods of using the same.

The present invention relates to trisodium diethylenetriamine pentaacetic acid (DTPA) prodrugs, such as, for example, DTPA di-ethyl esters. The invention further relates to compositions comprising DTPA prodrugs and methods of using the same.

The present invention relates to a process to prepare N,N-di(2-hydroxybenzyl) ethylenediamine-N,N-diacetic acid and salts thereof comprising a reaction between formaldehyde, ethylenediamine diacetic acid or a salt thereof and phenol at a pH of between 3 and 7 and a temperature below 60 C. wherein the reaction mixture contains 0.2 to 1.1 molar equivalents of alkali metalions on the molar amount of EDDA.