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 invention relates to a process for the preparation of Droxidopa by means of an improved enzymatic reduction of a compound of formula (II): (II), wherein R.sup.1, R.sup.2 is independent hydrogen, acetyl, R.sup.3 is hydrogen, a C1-C4 linear or branched alkyl group and R.sup.4 is hydrogen or an amine protecting group. ##STR00001##

The present invention relates to a process for the preparation of Droxidopa by means of an improved enzymatic reduction of a compound of formula (II): (II), wherein R.sup.1, R.sup.2 is independent hydrogen, acetyl, R.sup.3 is hydrogen, a C1-C4 linear or branched alkyl group and R.sup.4 is hydrogen or an amine protecting group. ##STR00001##

The present invention relates to a process for the preparation of Droxidopa by means of an improved enzymatic reduction of a compound of formula (II): (II), wherein R.sup.1, R.sup.2 is independent hydrogen, acetyl, R.sup.3 is hydrogen, a C1-C4 linear or branched alkyl group and R.sup.4 is hydrogen or an amine protecting group. ##STR00001##

The present invention relates to the chemical synthesis of α-amanitin and its derivatives. The present invention also relates to intermediate products of the α-amanitin synthesis.

The present invention relates to the chemical synthesis of α-amanitin and its derivatives. The present invention also relates to intermediate products of the α-amanitin synthesis.

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.

The present disclosure provides a method for photocleavage of an amide bond, the method has mild reaction conditions and can realize the cleavage of amide bonds by using light. The method comprises the following steps: subjecting 2,4-dinitrofluorobenzene to a reaction with an amino group of a substance represented by structural formula I with an α-amino acid at the end to produce a compound 1 represented by structural formula II; then under light irradiation, subjecting the compound 1 to a cleavage reaction of amide bond;

##STR00001##

Wherein, R1 is the side chain group of α-amino acid; R2 is: aryl, aliphatic hydrocarbon, —CH(R)—COOH or polypeptide.