Method for producing peptide compound, protective group-forming reagent, and aromatic heterocyclic compound

An aromatic heterocyclic compound represented by Formula (1a),

• in Formula (1a),
• a ring A represents an aromatic heterocyclic ring,
• YA represents —OH, —NHR, SH, or —X0, where R represents a hydrogen atom, an alkyl group, an aromatic group-substituted alkyl group, a heteroaromatic group-substituted alkyl group, or a 9-fluorenylmethoxycarbonyl group, and X0 represents Cl, Br, or I,
• RA's each independently represent a group represented by Formula (f1):
• in Formula (f1), the wavy line portion represents a bonding position to an aromatic heterocyclic ring, m9 represents an integer of 0 to 3, X9's each independently represent a single bond, —O—, —S—, —COO—, —OCO—, —OCONH—, —NHCONH—, —NHCO—, or —CONH—, R9's each independently represent a divalent aliphatic hydrocarbon group, Ar1 represents an (m10+1)-valent aromatic group or an (m10+1)-valent heteroaromatic group, m10 represents an integer of 1 to 3, X10's each independently represent a single bond, —O—, —S—, —COO—, —OCO—, —OCONH—, —NHCONH—, —NHCO—, or —CONH—, R10's each independently represent a monovalent aliphatic hydrocarbon group, and at least one of R10's is a monovalent aliphatic hydrocarbon group having 5 or more carbon atoms, and the ring A may further have a substituent in addition to RA,
• RB's each independently represent a monovalent aliphatic hydrocarbon, a (1+c)-valent aromatic group, or a (1+c)-valent heteroaromatic group,
• RC's each independently represent an aliphatic hydrocarbon group or an organic group having an aliphatic hydrocarbon group,
• m represents an integer of 0 to 2, a represents an integer of 0 to 5, and c represents an integer of 0 to 5,
• in a case where both a and c are 0, RB is a monovalent aliphatic hydrocarbon group,
• the number of carbon atoms in at least one aliphatic hydrocarbon group included in at least one of RA, RB, or RC is 12 or more, and
• a total number of carbon atoms in all aliphatic hydrocarbon groups included in all RA, RB, and RC is 40 or more,
• wherein the ring A is represented by any of Formula (11a), Formula (21a), or Formula 31a),
• in Formula (11a), any one of Rr15, Rr16, Rr17, or Rr18 is linked to the group which includes the carbon atom having YA in Formula (1a), Rr15 to Rr18 each independently represent a hydrogen atom or a substituent, RA is a group represented by Formula (f1), the number of carbon atoms in at least one aliphatic hydrocarbon group in RA is 14 or more, and Rr15 and Rr16, or Rr17 and Rr18 may be each independently linked to each other to form a ring,
• in Formula (21a), any one of Rr24, Rr25, or Rr26 is linked to the group which includes the carbon atom having YA in Formula (1a), Rr24 to Rr26 each independently represent a hydrogen atom or a substituent, RA is a group represented by Formula (f1), the number of carbon atoms in at least one aliphatic hydrocarbon group in RA is 14 or more, and Rr25 and Rr26 may be linked to each other to form a ring, and
• in Formula (31a), the wavy line portion represents a position linked to the group which includes the carbon atom having YA in Formula (1a), Xr31 represents an oxygen atom or a sulfur atom, Rr35 to Rr37 each independently represent a hydrogen atom, a substituent, or RA, RA's each independently represent a group represented by Formula (f1), the number of carbon atoms in at least one aliphatic hydrocarbon group in RA is 14 or more, and at least one of Rr35, Rr36, or Rr37 is RA and may be linked to Rr36 to form a ring.

An aromatic heterocyclic compound represented by Formula (1a),

• wherein, in Formula (1a),
• a ring A represents an aromatic heterocyclic ring,
• YA represents —OH, —NHR, SH, or —X0, where R represents a hydrogen atom, an alkyl group, an aromatic group-substituted alkyl group, a heteroaromatic group-substituted alkyl group, or a 9-fluorenylmethoxycarbonyl group, and X0 represents Cl, Br, or I,
• RA's each independently represent a group represented by
• Formula (f2),
• in Formula (f2), the wavy line portion represents a bonding position to an aromatic heterocyclic ring, m10 represents an integer of 1 to 3, m11 represents an integer of 0 to 3, X10's each independently represent a single bond, —O—, —S—, —COO—, —OCO—, —OCONH—, —NHCONH—, —NHCO—, or —CONH—, and R10's each independently represent a monovalent aliphatic hydrocarbon group having 5 or more carbon atoms,
• RB's each independently represent a monovalent aliphatic hydrocarbon, a (1+c)-valent aromatic group, or a (1+c)-valent heteroaromatic group,
• RC's each independently represent an aliphatic hvdrocarbon group or an organic group having an aliphatic hydrocarbon group,
• m represents an integer of 0 to 2, a represents an integer of 0 to 5, and c represents an integer of 0 to 5,
• in a case where both a and c are 0, RB is a monovalent aliphatic hydrocarbon group,
• the number of carbon atoms in at least one aliphatic hydrocarbon group included in at least one of RA, RB, or RC is 12 or more, and
• a total number of carbon atoms in all aliphatic hydrocarbon groups included in all RA, RB, and RC is 40 or more.