[185994-27-8] · C10H12INO4 · (MW 337.11)
(reagent used as a photolabile linker for solid-phase synthesis)
Physical Data: mp 57-59 °C.
Solubility: CH2Cl2, most organic solvents.
Form Supplied in: yellow powder.
Handling, Storage, and Precautions: prevent excess exposure to light and store at 4 °C.
The linker 5-(3-iodopropoxy)-2-nitrobenzyl alcohol (1) is conveniently prepared1 from commercially available 5-hydroxy-2-nitrobenzaldehyde by reaction with 1,3-diiodopropane in the presence of Cs2CO3. The carbonyl functionality of the resultant benzyl ether was then directly reduced to the benzylic alcohol with NaBH4 to give 1 in an overall yield of 92% (
Photolabile groups have served as linkers for the solid-phase synthesis of oligosaccharides.2-4 Compound 1 has been used as a photocleavable linkage in the synthesis of the heptasaccharide phytoalexin elicitor (HPE) (2).1
Glycosidation of linker 1 with appropriately protected monosaccharide unit 3 gave exclusively b-glycoside 4 in high yield. Attachment of 4, via nucleophilic displacement of the iodide in 4, to hydroxy-functionalized polystyrene resin gave resin-bound monosaccharide 5 (
Initial cleavage studies indicated irradiation5,6 of resin 5in THF at 25 °C afforded the released, protected monosaccharide fragment 6 in high yield (95%), signifying the feasibility of using 1 as a linker orthogonal to the other protecting groups on the sugar moiety (
This allowed oligosaccharide synthesis, such as the construction of HPE (2), by the iterative addition of monosaccharide fragments. This repetitive procedure involves the sequential selective deprotection of a hydroxy function on the sugar unit attached to the resin followed by glycosidation with a second monosaccharide component. Finally, light-mediated cleavage from the resin followed by global deprotection allowed the isolation of the desired heptasaccharide (as a mixture of a and b anomers).1
3-Amino-3-(2-nitrophenyl)propionic acid [5678-48-8];7
University of Southampton, Southampton, UK