Methods of preparing glufosinate

A method of preparing glufosinate represented by formula (I) or its salt or enantiomer, or a mixture of its enantiomers in any ratio, comprising the following steps:

• in absence of a solvent or in presence of an organic solvent, subjecting a compound of formula (II)
• to a reaction with any one of the following compounds or mixtures:
• a compound of formula (IV);
• a compound of formula (V);
• a compound of formula (IV) and a compound of formula (V);
• a compound of formula (IV) and a compound of formula (VII);
• a compound of formula (V) and a compound of formula (VII);
• or a compound of formula (IV), a compound of formula (V), and a compound of formula (VII), to obtain an intermediate;
• and
• hydrolyzing the intermediate under an acidic, neutral, or alkaline condition, to obtain a compound of formula (I);
• wherein
• X1 is halogen;
• X2 is halogen;
• Y is —OR3 or —N(R4) (R5);
• R1 and R2 are each independently selected from hydrogen, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C3-C6 cycloalkyl group, a three-membered to six-membered heterocycloalkyl group, a C6-C10 aryl group, or a five-membered to ten-membered heteroaryl group, or R1 and R2 form a three-membered to six-membered heterocycloalkyl group together with the N atom to which they are attached, wherein the C1-C6 alkyl group, the C2-C6 alkenyl group, the C2-C6 alkynyl group, the C3-C6 cycloalkyl group, the three-membered to six-membered heterocycloalkyl group, the C6-C10 aryl group, or the five-membered to ten-membered heteroaryl group is optionally substituted by halogen, a carboxyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C3-C6 cycloalkyl group, or a C6-C10 aryl group;
• R3, R4, and R5 are each independently selected from hydrogen, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, a C3-C6 cycloalkyl group, a three-membered to six-membered heterocycloalkyl group, a C6-C10 aryl group, or a five-membered to ten-membered heteroaryl group, or R4 and R5 form a three-membered to six-membered heterocycloalkyl group together with the N atom to which they are attached, wherein the C1-C6 alkyl group, the C2-C6 alkenyl group, the C2-C6 alkynyl group, the C3-C6 cycloalkyl group, the three-membered to six-membered heterocycloalkyl group, the C6-C10 aryl group, or the five-membered to ten-membered heteroaryl group is optionally substituted by halogen, a carboxyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C3-C6 cycloalkyl group, or a C6-C10 aryl group;
• and
• R9 and R10 are each independently selected from hydrogen, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, a C3-C6 cycloalkyl group, a three-membered to six-membered heterocycloalkyl group, a C6-C10 aryl group, or a five-membered to ten-membered heteroaryl group, or R9 and R10 form a three-membered to six-membered heterocycloalkyl group together with the N atom to which they are attached, wherein the C1-C6 alkyl group, the C2-C6 alkenyl group, the C2-C6 alkynyl group, the C3-C6 cycloalkyl group, the three-membered to six-membered heterocycloalkyl group, the C6-C10 aryl group, or the five-membered to ten-membered heteroaryl group is optionally substituted by halogen, a carboxyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C3-C6 cycloalkyl group, or a C6-C10 aryl group.
• * denotes a chiral carbon atom.

A method of preparing glufosinate represented by formula (I) or its salt or enantiomer, or a mixture of its enantiomers in any ratio, comprising the steps of using any one of the following compounds or mixtures:

• a compound of formula (IV);
• a compound of formula (V);
• or a compound of formula (VII) and a compound of formula (VIII):
• wherein
• X2 is halogen;
• R1 and R2 are each independently selected from hydrogen, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, a C3-C6 cycloalkyl group, a three-membered to six-membered heterocycloalkyl group, a C6-C10 aryl group, or a five-membered to ten-membered heteroaryl group, or R1 and R2 form a three-membered to six-membered heterocycloalkyl group together with the N atom to which they are attached, wherein the C1-C6 alkyl group, the C2-C6 alkenyl group, the C2-C6 alkynyl group, the C3-C6 cycloalkyl group, the three-membered to six-membered heterocycloalkyl group, the C6-C10 aryl group, or the five-membered to ten-membered heteroaryl group is optionally substituted by halogen, a carboxyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C3-C6 cycloalkyl group, or a C6-C10 aryl group;
• R9 and R10 are each independently selected from hydrogen, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, a C3-C6 cycloalkyl group, a three-membered to six-membered heterocycloalkyl group, a C6-C10 aryl group, or a five-membered to ten-membered heteroaryl group, or R9 and R10 form a three-membered to six-membered heterocycloalkyl group together with the N atom to which they are attached, wherein the C1-C6 alkyl group, the C2-C6 alkenyl group, the C2-C6 alkynyl group, the C3-C6 cycloalkyl group, the three-membered to six-membered heterocycloalkyl group, the C6-C10 aryl group, or the five-membered to ten-membered heteroaryl group is optionally substituted by halogen, a carboxyl group, a hydroxyl group, a cyano group, an amino group, a nitro group, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C3-C6 cycloalkyl group, or a C6-C10 aryl group.
• * denotes a chiral carbon atom.