Synthesis of morpholino oligomers using doubly protected guanine morpholino subunits
View Patent ↗Morpholino compounds are provided having the structure: where R 1 is selected from the group consisting of lower alkyl, di(lower alkyl)amino, and phenyl; R 2 is selected from the group consisting of lower alkyl, monocyclic arylmethyl, and monocyclic (aryloxy)methyl; R 3 is selected from the group consisting of triarylmethyl and hydrogen; and Y is selected from the group consisting of: a protected or unprotected hydroxyl or amino group; a chlorophosphoramidate group; and a phosphorodiamidate linkage to the ring nitrogen of a further morpholino compound or a morpholino oligomer. Such compounds include doubly protected morpholino guanine (MoG) monomers. Also described is their use in synthesis of morpholino oligomers.
1. A morpholino compound having the following structure I:
wherein:
R 1 is lower alkyl, di(lower alkyl)amino or phenyl;
R 2 is lower alkyl, monocyclic arylmethyl or monocyclic (aryloxy)methyl;
R 3 is triarylmethyl or hydrogen; and
Y is a protected or unprotected hydroxyl group, a protected or unprotected amino group, a chlorophosphoramidate group, a phosphorodiamidate linkage to the morpholino ring nitrogen of a morpholino subunit monomer, a phosphorodiamidate linkage to the morpholino ring nitrogen of a morpholino subunit in a morpholino oligomer or a linkage to a solid support.
2. The compound of claim 1 , wherein Y is a protected or unprotected hydroxyl group or a chlorophosphoramidate group.
3. The compound of claim 2 , wherein Y is a trialkylsilyl-protected hydroxyl group or an unprotected hydroxyl group.
4. The compound of claim 2 , wherein Y is a chlorophosphoramidate group having the following structure:
5. The compound of claim 1 , wherein R 3 is trityl, 4-methoxytrityl, 4-methyltrityl, 4,4′-dimethyltrityl or 4,4′,4″-trimethyltrityl.
6. The compound of claim 1 , wherein R 1 is lower alkyl.
7. The compound of claim 6 , wherein R 1 is —C(CH 3 ) 3 .
8. The compound of claim 1 , wherein R 2 is benzyl or —CH(CH 3 ) 2 .
9. A method of synthesizing a morpholino oligomer, the method comprising:
(a) reacting
a solid-phase-supported morpholino subunit monomer comprising an unprotected morpholino ring nitrogen
with a first morpholino subunit monomer comprising a triarylmethyl-protected morpholino ring nitrogen and an activated phosphoramidate group on a 5′-exocyclic carbon, thereby forming a phosphorodiamidate linkage between the 5′-exocyclic carbon of the first morpholino subunit monomer and the unprotected morpholino ring nitrogen of the solid-phase-supported morpholino subunit monomer;
(b) deprotecting the triarylmethyl-protected morpholino ring nitrogen to form a product comprising an unprotected morpholino ring nitrogen;
(c) optionally reacting the product from step (b) with a further morpholino subunit monomer comprising a triarylmethyl-protected morpholino ring nitrogen and an activated phosphoramidate group on a 5′-exocyclic carbon, thereby forming a phosphorodiamidate linkage between the 5′-exocyclic carbon of the further morpholino subunit monomer and the unprotected morpholino ring nitrogen of the product from step (b); and
(d) optionally repeating steps (b) and (c) one or more times;
wherein at least one of the first morpholino subunit monomer, the further morpholino subunit monomer or the solid-phase-supported morpholino subunit monomer is a doubly protected guanine morpholino compound having the following structure I:
wherein:
R 1 is lower alkyl, di(lower alkyl)amino or phenyl;
R 2 is lower alkyl, monocyclic arylmethyl or monocyclic (aryloxy)methyl;
R 3 is triarylmethyl or hydrogen; and
Y is a chlorophosphoramidate group or a linkage to a solid support.
10. The method of claim 9 , wherein Y is a chlorophosphoramidate group having the following structure:
11. The method of claim 9 , wherein R 3 is trityl, 4-methoxytrityl, 4-methyltrityl, 4,4′-dimethyltrityl or 4,4′,4″-trimethyltrityl.
12. The method of claim 9 , wherein R 1 is lower alkyl.
13. The method of claim 12 , wherein R 1 is —C(CH 3 ) 3 .
14. The method of claim 9 , wherein R 2 is benzyl or —CH(CH 3 ) 2 .
15. The compound of claim 1 , wherein the compound has the following structure:
wherein Y is a linkage to a solid support or a chlorophosphoramidate group having the following structure:
16. The method of claim 9 , wherein at least one of the first morpholino subunit monomers, the further morpholino subunit monomer or the solid-phase-supported morpholino subunit monomer has the following structure:
wherein Y is a linkage to a solid support or a chlorophosphoramidate group having the following structure: