Abstract: A novel agent for introducing a protecting group for a hydroxy group and/or a mercapto group that can be introduced and removed under mild conditions is provided. The agent for introducing a protecting group for a hydroxy group and/or mercapto group of a substrate compound having the hydroxy group and/or mercapto group is represented by the following formula (I), wherein A represents a ring structure having 1 to 5 rings in which two carbon atoms of an adjacent benzene ring are included, the ring structure comprises a substituted or unsubstituted five-membered ring or six-membered ring and optionally include a heterocycle; each of R1, R2, R3, and R4 is independently a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms; and X is a halogen atom or OSO2R5 (R5=an aryl group or an alkyl group).

Abstract: A novel agent for introducing a protecting group for a hydroxy group and/or a mercapto group that can be introduced and removed under mild conditions is provided. The agent for introducing a protecting group for a hydroxy group and/or mercapto group of a substrate compound having the hydroxy group and/or mercapto group is represented by the following formula (I), wherein A represents a ring structure having 1 to 5 rings in which two carbon atoms of an adjacent benzene ring are included, the ring structure comprises a substituted or unsubstituted five-membered ring or six-membered ring and optionally include a heterocycle; each of R1, R2, R3, and R4 is independently a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms; and X is a halogen atom or OSO2R5 (R5=an aryl group or an alkyl group).