Method for producing peptide compound, protective group-forming reagent, and condensed polycyclic compound

A method for producing a peptide compound, comprising:

• a step of using a compound represented by Formula (1),
• in Formula (1),
• Y1 represents —SH, Br, Cl, —OH, —NH2, —NHEt, where Et represents an ethyl group, or —NHFmoc, where Fmoc represents a 9-fluorenylmethoxycarbonyl group,
• Y2 represents —O—, —S—, —CH═CH—, —C(CH3)═C(CH3)—, —CH2—CH2—, —C(CH3)2—,
• R1, R2, R5, R7, and R8 each represent a hydrogen atom,
• R3 represents a hydrogen atom,
• —OC22H45, or —OC12H24OC22H45,
• R4 represents a hydrogen atom or —NH2,
• R6 represents a hydrogen atom,
• —OC22H45, or —OC12H24OC22H45,
• provided that at least one of the following (i), (ii), or (iii) is satisfied:
• (i) Y2 represents
• (ii) R3 represents
• —OC22H45, or —OC12H24OC22H45;
• or
• (iii) R6 represents
• —OC22H45, or —OC12H24OC22H45.