Morpholino oligonucleotide manufacturing method

A morpholino nucleotide represented by formula (I):

• wherein
• m is any integer of not less than 0,
• P1 is a hydrogen atom, or a temporary protecting group removable under acidic conditions,
• P2 is a protecting group having an alkyl group having not less than 10 and not more than 300 carbon atoms and/or an alkenyl group having not less than 10 and not more than 300 carbon atoms or a protecting group removable under conditions different from those for P1,
• Base1 is a nucleic acid base optionally protected by a protecting group,
• Base2 in the number of m are each independently a nucleic acid base optionally protected by a protecting group,
• each X in the number of m is independently a di C1-6 alkylamino group, or a 1-piperazinyl group wherein a nitrogen atom at the 4-position is protected by a protecting group and further optionally substituted, and
• W in the number of m are each an oxygen atom,
• provided that:
• 1) at least one of said protecting group when Base1 is protected by a protecting group, any protecting group when any Base2 in the number of m are protected by a protecting group, and a protecting group for P2 is a protecting group having an alkyl group having not less than 10 and not more than 300 carbon atoms and/or an alkenyl group having not less than 10 and not more than 300 carbon atoms, and
• 2) when P2 is a protecting group having a linear alkyl group having not less than 10 and not more than 300 carbon atoms and/or a linear alkenyl group having not less than 10 and not more than 300 carbon atoms, at least one of Base1 and any Base2 in the number of m is a nucleic acid base protected by a protecting group having an alkyl group having not less than 10 and not more than 300 carbon atoms and/or an alkenyl group having not less than 10 and not more than 300 carbon atoms.