A method for producing an alkylamine derivative having a urea bond represented by formula (I), or a salt thereof, comprises the following steps (a) and (b), step (a):

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and step (b): deprotecting as necessary the reaction product obtained in step (a). The production method suitable for industrialization of the alkylamine derivative having a urea bond represented by formula (I), which is a compound highly useful as an agent having CaSR agonist effects is provided.

To deprotect an alcoholic hydroxyl group protected by a t-butyldimethylsilyl group without influencing a functional group unstable to an acid. In the presence of a solvent, an alcohol having a hydroxyl group protected by a t-butyldimethylsilyl group is deprotected in the presence of an acid or an acid salt having a pKa of from 1.0 to 3.0 in water.

To deprotect an alcoholic hydroxyl group protected by a t-butyldimethylsilyl group without influencing a functional group unstable to an acid. In the presence of a solvent, an alcohol having a hydroxyl group protected by a t-butyldimethylsilyl group is deprotected in the presence of an acid or an acid salt having a pKa of from 1.0 to 3.0 in water.

A method for protecting a phenol group on a precursor compound is provided. The method includes reacting the phenol group with dihydropyran in an acid catalyzed protection reaction and quenching the protection reaction with a strong base within less than about 60 seconds to form a protected precursor compound.

A method for protecting a phenol group on a precursor compound is provided. The method includes reacting the phenol group with dihydropyran in an acid catalyzed protection reaction and quenching the protection reaction with a strong base within less than about 60 seconds to form a protected precursor compound.

A method for producing a dipeptide that has a protected N-terminal and is represented by formula (1) or a salt of the dipeptide, said method comprising condensing an -monosubstituted amino acid that has a protected N-terminal and is represented by formula (2) or glycine or a salt thereof with a disubstituted amino acid that is represented by formula (3) or a salt thereof in the presence of a condensing agent [in each of the formulae, substituents are as defined in the description or the like]. ##STR00001##

A method for producing a dipeptide that has a protected N-terminal and is represented by formula (1) or a salt of the dipeptide, said method comprising condensing an -monosubstituted amino acid that has a protected N-terminal and is represented by formula (2) or glycine or a salt thereof with a disubstituted amino acid that is represented by formula (3) or a salt thereof in the presence of a condensing agent [in each of the formulae, substituents are as defined in the description or the like]. ##STR00001##

Provided is a method that prevents decreases in solubility in an organic solvent when elongating a peptide chain by a peptide coupling reaction and improves the reactivity of a peptide chain and the operability in a purification process. The method makes it possible to obtain a polypeptide compound represented by formula (P1) by performing amide formation reaction of the carboxyl group on the right side of the amino acid or the peptide compound in formula (R1) with the amino group on the left side of the amino acid or the peptide ester compound in formula (R2) in which the terminal carboxyl group is protected by a silicon-containing hydrophobic substituent TAG(Si).

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Provided herein is a method for removing a tert-butoxycarbonyl (Boc) group in a compound having a Boc group on a nitrogen atom, comprising treating the compound with a trifluoromethanesulfonic acid metal salt (metal triflate: M(OTf).sub.n) or rare-earth metal halide (MX.sub.n) in the presence of a base to obtain a compound in which the Boc group is converted to H.

Provided herein is a method for removing a tert-butoxycarbonyl (Boc) group in a compound having a Boc group on a nitrogen atom, comprising treating the compound with a trifluoromethanesulfonic acid metal salt (metal triflate: M(OTf).sub.n) or rare-earth metal halide (MX.sub.n) in the presence of a base to obtain a compound in which the Boc group is converted to H.