Synthetic tools for studying the chemical biology of InsP8

Synthetic mimics of InsP8, Nature's most phosphorylated inositol phosphate, interact differentially with the kinase PPIP5K2 and provide stabilised, complementary tools to investigate this orphan signal.


General Chemistry Methods
Chemicals were purchased from Sigma-Aldrich, Acros, or Alfa Aesar and used without further purification. Anhydrous solvents from Sigma-Aldrich were used without further treatment.

Determination of Absolute Configurations of Monocamphanate Esters 12 and 13 D-1,2,4,6-tetra-O-benzyl-3-O-methyl-myo-inositol (14)
To a solution of the less polar monocamphanate 12 (200 mg, 0.277 mmol) in dry THF (4 mL) at 0 °C was added a strictly catalytic amount of PTSA (2 mg), followed by 2-methoxypropene (0.60 mL, 0.45 g, 6.2 mmol). After 10 min, the cooling bath was removed and the solution was allowed to reach room temperature over 1 hour. TLC (EtOAc:light petroleum 1:3) showed conversion of 12 (Rf 0.36) into a less polar product (Rf 0.54). The solution was stirred at room temperature and a solution of LiOH.H2O (118 mg, 2.8 mmol) in deionised water (2 mL) and methanol (2 mL) was added. After 2 h, TLC (EtOAc:light petroleum 1:3) showed that S9 the camphanate ester had been cleaved, giving a slightly more polar product (Rf 0.40). The volatile solvents were removed by evaporation under reduced pressure, and then more deionised water (20 mL) was added, followed by dichloromethane (20 mL). The organic layer was separated and the aqueous layer was re-extracted with more dichloromethane (20 mL).
The combined organic layers were dried (MgSO4) and concentrated. The residue was redissolved in dry DMF (5 mL) and sodium hydride (110 mg of a 60% suspension in oil, 2.8 mmol) was added. The suspension was stirred at rt for 5 min, then cooled to 0 °C under N2.
Methyl iodide (137 μL, 2.2 mmol) was added dropwise and stirring was continued at 0 °C for a further 30 min before the cooling bath was removed and the solution was stirred at rt for a
The resulting clear solution was allowed to cool, neutralised by addition of solid CO2 pellets, and then concentrated. The residue was partitioned between water and dichloromethane (40 mL each) and the organic layer was separated, dried (MgSO4) and concentrated.
The solution was concentrated and methanol (5 mL