Method for producing alpha-fluoroacrylic acid

A method for producing a compound represented by formula (1) or a salt thereof:

• wherein
• R1 and R2 are identical or different, and each represents an alkyl group, a fluoroalkyl group, an aryl group optionally having one or more substituents, a halogen atom, or a hydrogen atom;
• R3o is a hydrogen atom or R3;
• and
• R3 is an alkyl group, a fluoroalkyl group, or an aryl group optionally having one or more substituents,
• the method comprising step A of reacting a compound represented by formula (2):
• wherein the symbols in the formula are as defined above,
• with carbon monoxide and an alcohol represented by formula (3):
• R3—OH (3)
• wherein the symbol in the formula is as defined above,
• in the presence of
• palladium,
• a double bond-containing compound (α) represented by formula (α):
• wherein
• Rb1 is a hydrogen atom or a C1-6 alkyl group,
• Rb2 is a hydrogen atom or a C1-6 alkyl group,
• Yb1 is ═O or ═CH—Ryb1,
• Yb2 is —H, ═O or ═CH—Ryb2,
• Ryb1 is a hydrogen atom or a C6-14 aryl group,
• Ryb2 is a C6-14 aryl group,
• or
• Rb1 and Yb1, taken together with the adjacent carbon atom, may form an aromatic hydrocarbon ring,
• Lb is a bond, C1-3 alkanediyl optionally having one or more side chains, or —C(═O)—,
• or
• Ryb1 and Ryb2 may be linked to each other to form -Ly-, wherein Ly is linear
• C1-2 alkanediyl optionally having one or more side chains,
• wherein one of the side chains in Lb
• (1) may be linked to one of the side chains in Ly to form linear C1-2 hydrocarbon diyl, or
• (2) may be linked to Rb1 to form C3-4 alkanediyl,
• a diphosphine compound (β) having, on each phosphorus atom, at least one substituent selected from the group consisting of alkyl and cycloalkyl groups, and
• a base, with the proviso that, in the reaction, the palladium, taken together with the compound represented by formula (2), the double bond-containing compound (α), the diphosphine compound (β), or carbon monoxide, or with one or more of these, may form a palladium complex (A),
• to obtain the compound represented by formula (1) or a salt thereof.