Method for producing trisulfide compound or selenotrisulfide compound

A method for producing a trisulfide compound or a selenotrisulfide compound, comprising:

• oxidizing a disulfide compound with an oxidizing agent to obtain a sulfoxide compound;
• and
• allowing the obtained sulfoxide compound to react with a sulfur source or a selenium source to obtain a trisulfide compound or a selenotrisulfide compound,
• wherein obtaining the sulfoxide compound and obtaining the trisulfide compound or the selenotrisulfide compound are performed in a one-pot reaction,
• wherein the sulfur source is selected from the group consisting of sodium sulfide, potassium sulfide, sodium hydrosulfide, potassium hydrosulfide, and hydrogen sulfide, and the selenium source is selected from the group consisting of sodium selenide, potassium selenide, sodium hydroselenide, potassium hydroselenide, and hydrogen selenide, and
• wherein the disulfide compound is
• (1) a compound represented by R1—S—S—R2, wherein R1 and R2 may be the same or different, and each represents an alkyl group, each of which may be optionally substituted with one or more substituents selected from Substituent Group A, wherein
• Substituent Group A consists of a hydroxy group, an amino group optionally substituted with one or more substituents selected from Substituent Group B, and an oxo group, and
• Substituent Group B consists of an alkyl group optionally substituted with one or more substituents selected from the group consisting of a hydroxy group, an amino group, an oxo group, and an acetyl group, or
• (2) a compound represented by R3—S—S—R4, wherein R3 and R4 may be the same or different, and each represents a group in which an SH group is removed from cysteine optionally protected by a protective group or a group in which an SH group is removed from a cysteine-containing peptide optionally protected by a protective group.