Oligosaccharide solid-phase synthesis coupling

Attachment of suitable linkers to the surface of silica can be achieved by transesterification with (3-aminopropyl)triethoxysilane, which leads to the support 2 (Figure 2.8) [198-200]. Alternatively, silica can be functionalized by reaction with alkyltri-chlorosilanes [201]. For the solid-phase synthesis of oligonucleotides, supports with a longer spacer, such as that in 3, have proven more convenient than 2 [202-206]. Supports 3, so-called LCAA-CPG (long chain alkylamine CPG [194,195]), are commercially available (typical loading 0.1 mmol/g) and are currently the most commonly used supports for the synthesis of oligonucleotides. For this purpose, protected nucleosides are converted into succinic acid monoesters, and then coupled to LCAA-CPG. CPG functionalized with a 3-mercaptopropyl linker has been used for the solid-phase synthesis of oligosaccharides [207]. 

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