Oligonucleotide synthesis on solid support

A functionalized solid support of formula (I), or a salt thereof,

• wherein:
• A is a solid support material;
• L1 -silyl-C2-4alkylene-NH—C2-10alkylene-NHC(O)—C2-10alkylene;
• L2, at each occurrence, is independently —(CH2CH2O)m—, —(CHCH3CH2O)m—, or —(CH2CHCH3O)m—;
• G1 is —P(O)(R1)-L3-R2, hydrogen, or PG1;
• R1, at each occurrence, is independently —OR1a or R1a;
• R1a, at each occurrence, is independently C1-10alkyl, C2-10alkenyl, C2-10alkynyl, C3-10cycloalkyl, or C5-10cycloalkenyl, wherein R1a is optionally substituted with 1-6 substituents independently selected from the group consisting of cyano, halogen, oxo, OH, —OC1-4alkyl, —OC1-4haloalkyl, or C3-6cycloalkyl, the C3-6cycloalkyl being optionally substituted with halogen or C1-4alkyl;
• L3 is —(OCH2CH2)p—, —(OCHCH3CH2)p—, —(OCH2CHCH3)p—, —OC2-10alkylene-, —OC0-4alkylene-C3-10cycloalkylene-C0-4alkylene-, or —OC0-4alkylene-phenylene-C0-4alkylene-, wherein the alkylene in L3 is optionally substituted with 1-6 halogen, and the cycloalkylene and phenylene are optionally substituted with 1-4 substituents independently selected from the group consisting of halogen, C1-4alkyl, C1-4haloalkyl, cyano, —OC1-4alkyl, and —OC1-4haloalkyl;
• R2 is —NR2aR2b;
• R2a is hydrogen, C1-6alkyl, C1-6haloalkyl, C3-6cycloalkyl, or —C1-3alkylene-C3-6cycloalkyl;
• R2b is C(O)-L4-G1a, hydrogen, PG2, C(O)-L4-OH, C(O)-L4-OPG3, C(O)-L5-H, C(O)-L5-PG1, C(O)-L5-P(O)(R1)-G1a, C(O)-L5-P(O)(OH)-G1a, or C(O)-L6-G1a, or
• R2a and R2b, together with the nitrogen to which they attach form a protected nitrogen atom;
• L4 is L7-C(O) or C(O);
• L5 is L7-O;
• L6 is L7-Si(C1-4alkyl)2;
• L7 is a divalent chemical linker composed of atoms selected from the group consisting of carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen,
• wherein
• (a) the atoms of the divalent linker are arranged to form an optionally substituted chain, an optionally substituted ring, or a combination of optionally substituted chain(s) and ring(s);
• and
• (b) the chain(s), ring(s), or combination thereof comprise a 1- to 20-membered contiguous linear arrangement of atoms selected from the group consisting of carbon, oxygen, nitrogen, sulfur, phosphorus, and silicon;
• G1a is a nucleotide moiety or a nucleoside moiety;
• PG1 is a hydroxy protecting group;
• PG2 is an amino protecting group;
• PG3 is carboxylic acid protecting group;
• m and p are independently an integer from 3 to 10;
• and
• n is an integer from 1 to 20.