The present invention relates to compounds which are useful for efficient synthesis of 2-amino-4-oxobicyclo[3.1.0]hexane-2,6-dicarboxylic acids. The compounds according to the present invention comprise 2-oxobicyclo[3.1.0]hexane-6-carboxylic acid derivatives represented by the formula as follows: [wherein, R1 represents a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group, a C3-C6 cycloalkyl C1-C6 alkyl group, an aryl group, an aryl C1-C6 alkyl group, a C1-C6 alkoxy C1-C6 alkyl group, a C1-C6 hydroxyalkyl group, a C1-C6 alkylthio C1-C6 alkyl group, a C1-C6 mercaptoalkyl group, a tetrahydrofuranyl group, or a tetrahydropyranyl group; R2 and R3 are identical or different, and each represents a C1-C6 alkyl group, a C3-C6 cycloalkyl group, a C3-C6 cycloalkyl C1-C6 alkyl group, an aryl group, or an aryl C1-C6 alkyl group, or alternatively, R2 and R3 together represent —(CH2)n— (wherein n represents 2 or 3); and Y1 and Y2 are identical or different, and each represents a sulfur atom, an oxygen atom, or a nitrogen atom].