Enzyme-Assisted Total Synthesis of the Optical Antipodes d-myo-Inositol 3,4,5-Trisphosphate and d-myo-Inositol 1,5,6-Trisphosphate:  Aspects of Their Structure−Activity Relationship to Biologically Active Inositol Phosphates

Abstract

Unambiguous total syntheses of both optical antipodes of the enantiomeric pair D-myo-inositol 3,4,5-trisphosphate (Ins(3,4,5)P3) and D-myo-inositol 1,5,6-trisphosphate (Ins(1,5,6)P3) are described. The ring system characteristic of myo-inositol was constructed de novo from p-benzoquinone. X-ray data for the enzymatically resolved (1S,2R,3R,4S)-1,4-diacetoxy-2,3-dibromocyclohex-5-ene enabled the unequivocal assignment of the absolute configuration. Subsequent transformations under stereocontrolled conditions led to enantiopure C2-symmetrical 1,4-(di-O-benzyldiphospho)conduritol B derivatives. Their synthetic potential was exploited to prepare Ins(3,4,5,6)P4 and Ins(1,4,5,6)P4 in three steps. With a recently identified and partially purified InsP5/InsP4 phosphohydrolase from Dictyostelium discoideum, these enantiomers could be converted to the target compounds, Ins(3,4,5)P3 and Ins(1,5,6)P3, on a preparative scale. An HPLC system employed for both purification of the inositol phosphates and analytical runs ensured that the products were isomerically homogeneous. The sensitivity of detection achieved by a complexometric postcolumn derivatization method indicates that the complexation properties of Ins(3,4,5)P3/Ins(1,5,6)P3 resemble those of Ins(1,2,3)P3, a compound with antioxidant potential. The set of inositol phosphates synthesized was used to clarify structural motifs important for molecular recognition by p42(IP4), a high-affinity Ins(1,3,4,5)P4/PtdIns(3,4,5)P3-specific binding protein from pig cerebellum.

Flexible Stereo‐ and Regioselective Synthesis of myo‐Inositol Phosphates(Part 1): Via Symmetrical Conduritol B Derivatives

“…The building blocks (+)-and (-)-2, (-)-and (+)-3, and their precursors were prepared according to literature methods, [10,11] as were 1,4-di-O-benzylconduritol B (14) [12] and 1,4-bis(di-O-benzylphospho)conduritol B (17). [11] Purification and Analysis of Inositol Tris-and Tetrakisphosphates (HPLC-MDD): Inositol phosphates were purified and analyzed by the HPLC-MDD method described previously. [11,22] The compounds were separated by anion-exchange chromatography on a MonoQ HR10/10 column (Pharmacia).…”

“…[11] Purification and Analysis of Inositol Tris-and Tetrakisphosphates (HPLC-MDD): Inositol phosphates were purified and analyzed by the HPLC-MDD method described previously. [11,22] The compounds were separated by anion-exchange chromatography on a MonoQ HR10/10 column (Pharmacia). To purify inositol phosphates, a linear gradient of HCl was applied (0 min 0.2 mm HCl; 70 min 0.5 m HCl; flow rate 1.5 mL min -1 ).…”

“…The known diacetoxydibromocyclohex-5-enes (+)-3 and (-)-3 [or the corresponding diols (-)-and (+)-2] were used as the enantiomerically pure building blocks [10,11] for the synthesis of all the myo-inositol derivatives described. Racemic 3 can easily be prepared from p-benzoquinone in three steps and 70 % overall yield.…”

“…The diacetate (+)-3 could be converted in the same way into the enantiomer (-)-14. The diphosphorylated conduritol B derivative (+)-17 was synthesized [11] by double allylic opening with dibenzyl phosphate of anti-benzene dioxide (-)-16, which was synthesized in one step from the enantiomeric building blocks (Scheme 2).…”

“…[13] Phosphorylation of (+)-22 and deprotection by Pd/C-catalyzed hydrogenation gave myo-Ins(1,2,4,5)P 4 [(-)-11] in 70% yield over two steps. As previously described, it is possible to synthesize the tetrakisphosphate isomers myo-Ins(1,2,3,6)P 4 [(+)-12] [13,14] and myo-Ins (3,4,5,6)P 4 [(+)-13] [11] from the precursor (+)-17.…”