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Synthesis of D- and L-myo-inositol 1,2,4,6-tetrakisphosphate, regioisomers of myo-inositol 1,3,4,5 tetrakisphosphate: activity against Ins(1,4,5)P3 binding proteins.

We report here the synthesis of D- and L-myo-inositol 1,2,4,6-tetrakisphosphate 3a and 3b and the racemic modification 3ab. Racemic myo-inositol 1,2,4,6-tetrakisphosphate 3ab was synthesised from DL-1,2,4,6-tetra-O-allyl-myo-inositol 9ab. Benzylation and de-allylation provided the tetraol 11ab, which was phosphitylated in the presence of bis(benzyloxy)diisopropylaminophosphine and 1H-tetrazole, then oxidised to give the fully protected 1,2,4,6-tetrakisphosphate 13ab. Hydrogenolysis of 13ab and purification of product by ion exchange chromatography gave racemic myo-inositol 1,2,4,6-tetrakisphosphate 3ab, which showed no demonstrable agonism or antagonism for Ca2+ release at 200 microM in permeabilised hepatocytes. The chiral derivatives, D-3a and L-myo-inositol 1,2,4,6-tetrakisphosphate 3b were synthesised from 5-O-benzyl-1,4,6-tri-O-p-methoxybenzyl-myo-inositol 19ab, which was resolved using R-(-)-O-acetylmandelic acid providing two diastereoisomers 21 and 22 which were separated and deacylated to give the corresponding enantiomers. Further transformations gave the corresponding chiral 1,2,4,6-tetraols which were phosphitylated, oxidised, deprotected and purified as for the racemic mixture. The enantiomeric tetrakisphosphates 3a and 3b were evaluated for inhibition of the metabolic enzymes inositol 1,4,5-trisphosphate 5-phosphatase and 3-kinase in comparison with the enantiomers of another synthetic regioisomer D- and L-myo-inositol 1,2,4,5-tetrakisphosphate. Both D- and L-myo-inositol 1,2,4,6-tetrakisphosphate inhibit 5-phosphatase with an IC50 value of 3.8 microM and 14 microM, repectively. However, both enantiomers were poorly recognised by the 3-kinase enzyme, with IC50 values greater than 100 microM. The enantiomers of the 1,2,4,5-tetrakisphosphate showed the same relative pattern of activity towards the two enzymes but were more potent against 5-phosphatase (0.47 microM and 3 microM respectively).

Dual aromatase-sulfatase inhibitors based on the anastrozole template: synthesis, in vitro SAR, molecular modelling and in vivo activity.

The synthesis and biological evaluation of a series of novel Dual Aromatase-Sulfatase Inhibitors (DASIs) are described. It is postulated that dual inhibition of the aromatase and steroid sulfatase enzymes, both responsible for the biosynthesis of oestrogens, will be beneficial in the treatment of hormone-dependent breast cancer. The compounds are based upon the Anastrozole aromatase inhibitor template which, while maintaining the haem ligating triazole moiety crucial for enzyme inhibition, was modified to include a phenol sulfamate ester motif, the pharmacophore for potent irreversible steroid sulfatase inhibition. Adaption of a synthetic route to Anastrozole was accomplished via selective radical bromination and substitution reactions to furnish a series of inhibitory aromatase pharmacophores. Linking these fragments to the phenol sulfamate ester moiety employed S(N)2, Heck and Mitsunobu reactions with phenolic precursors, from where the completed DASIs were achieved via sulfamoylation. In vitro, the lead compound, 11, had a high degree of potency against aromatase (IC(50) 3.5 nM), comparable with that of Anastrozole (IC(50) 1.5 nM) whereas, only moderate activity against steroid sulfatase was found. However, in vivo, 11 surprisingly exhibited potent dual inhibition. Compound 11 was modelled into the active site of a homology model of human aromatase and the X-ray crystal structure of steroid sulfatase.

Synthesis of adenophostin A analogues conjugating an aromatic group at the 5'-position as potent IP3 receptor ligands.

Previous structure-activity relationship studies of adenophostin A, a potent IP(3) receptor agonist, led us to design the novel adenophostin A analogues 5a-c, conjugating an aromatic group at the 5'-position to develop useful IP(3) receptor ligands. The common key intermediate, a D-ribosyl alpha-D-glucoside 10alpha, was stereoselectively synthesized by a glycosidation with the 1-sulfinylglucoside donor 11, which was conformationally restricted by a 3,4-O-cyclic diketal protecting group. After introduction of an aromatic group at the 5-position of the ribose moiety, an adenine base was stereoselectively introduced at the anomeric beta-position to form 7a-c, where the tetra-O-i-butyryl donors 9a-c were significantly more effective than the corresponding O-acetyl donor. Thus, the target compounds 5a-c were synthesized via phosphorylation of the 2', 3' ', and 4' '-hydroxyls. The potencies of compounds 5a-c for Ca(2+) release were shown to be indistinguishable from that of adenophostin A, indicating that bulky substitutions at the 5'-position of adenophostin A are well-tolerated in the receptor binding. This biological activity of 5a-c can be rationalized by molecular modeling using the ligand binding domain of the IP(3) receptor.

Benzene polyphosphates as tools for cell signalling: inhibition of inositol 1,4,5-trisphosphate 5-phosphatase and interaction with the PH domain of protein kinase Balpha.

Novel benzene polyphosphates were synthesised as inositol polyphosphate mimics and evaluated against type-I inositol 1,4,5-trisphosphate 5-phosphatase, which only binds soluble inositol polyphosphates, and against the PH domain of protein kinase Balpha (PKBalpha), which can bind both soluble inositol polyphosphates and inositol phospholipids. The most potent trisphosphate 5-phosphatase inhibitor is benzene 1,2,4-trisphosphate (2, IC(50) of 14 microM), a potential mimic of D-myo-inositol 1,4,5-trisphosphate, whereas the most potent tetrakisphosphate Ins(1,4,5)P(3) 5-phosphatase inhibitor is benzene 1,2,4,5-tetrakisphosphate, with an IC(50) of 4 microM. Biphenyl 2,3',4,5',6-pentakisphosphate (4) was the most potent inhibitor evaluated against type I Ins(1,4,5)P(3) 5-phosphatase (IC(50) of 1 microM). All new benzene polyphosphates are resistant to dephosphorylation by type I Ins(1,4,5)P(3) 5-phosphatase. Unexpectedly, all benzene polyphosphates studied bind to the PH domain of PKBalpha with apparent higher affinity than to type I Ins(1,4,5)P(3) 5-phosphatase. The most potent ligand for the PKBalpha PH domain, measured by inhibition of biotinylated diC(8)-PtdIns(3,4)P(2) binding, is biphenyl 2,3',4,5',6-pentakisphosphate (4, K(i)=27 nm). The approximately 80-fold enhancement of binding relative to parent benzene trisphosphate is explained by the involvement of a cation-pi interaction. These new molecular tools will be of potential use in structural and cell signalling studies.

Synthesis of L-scyllo-inositol 1,2,4-trisphosphate, scyllo-inositol 1,2,4,5-tetrakisphosphate and phosphorothioate and DL-2-deoxy-2-fluoro-myo-inositol 1,4,5-trisphosphate: Optical resolution of DL-1-O-allyl-3,6-di-O-benzyl-4,5-O-isopropylidene-scyllo-inositol

Routes for the synthesis of scyllo-inositol tris- and tetrakis-phosphates and 2-deoxy-2-fluoro-myo-inositol 1,4,5-trisphosphate from myo-inositol have been devised. For DL-scyllo-inositol 1,2,4-trisphosphate, DL-1-O-allyl-3,6-di-O-benzyl-4-5-O-isopropylidene-scyllo-inositol was prepared from the triflate of DL-1-O-allyl-3,6-di-O-benzyl-4,5-O-isopropylidene-myo-inositol by inversion at C-2. Removal of the isopropylidene group and phosphorylation gave the protected trisphosphate. Deblocking with sodium in liquid ammonia afforded racemic scyllo-inositol 1,2,4-trisphosphate. DL-1-O-Allyl-3,6-di-O-benzyl-4,5-O-isopropylidene-scyllo-inositol was resolved into its enantiomers by means of the crystalline 2-O-camphanate ester. The structure of one diastereoisomer, 1D-O-allyl-3,6-di-O-benzyl-2-O-[( - )-camphanoyl]-4,5-O-isopropylidene-scyllo-inositol was determined by single-crystal X-ray crystallography. 1D-( + )-1-O-Allyl-3,6-di-O-benzyl-4,5-O-isopropylidene-scyllo-inositol was used to prepare 1L-( - )-scyllo-inositol 1,2,4-trisphosphate in a fashion analogous to the racemic modification. DL-1-O-Allyl-3,6-di-O-benzyl-scyllo-inositol was isomerised to the (Z)-prop-1-enyl derivative. The propenyl group was then removed to give the meso-1,4-di-O-benzyl-scyllo-inositol. Phosphitylation followed by oxidation or sulfoxidation gave the fully protected tetrakis-phosphate or -phosphorothioate, respectively. After deblocking and purification, scyllo-inositol 1,2,4,5-tetrakisphosphate and scyllo-inositol 1,2,4,5-tetrakisphosphorothioate were obtained. DL-1-O-Allyl-3,6-di-O-benzyl-4,5-O-isopropylidene-scyllo-inositol was isomerised to the 1-O-[(Z)-prop-1-enyl] derivative which was converted into the 2-0-triflate. Displacement of the triflate using tetrabutylammonium fluoride proceeded with inversion of configuration to give DL-3,6-di-O-benzyl-2-deoxy-2-fluoro-4,5-O-isopropylidene-1-O-([(Z)-prop-1-enyl]- myo-inositol. Removal of propenyl and isopropylidene groups afforded DL-3,6-di-O-benzyl-2-deoxy-2-fluoro-myo-inositol, which was phosphitylated and the product oxidised to give the fully protected 2-fluoro trisphosphate. Deprotection furnished DL-2-deoxy-2-fluoro-myo-inositol 1,4,5-trisphosphate. These compounds will be useful probes for investigation of the polyphosphoinositide pathway of cellular signalling.

2-Alkylsulfanyl estrogen derivatives: synthesis of a novel class of multi-targeted anti-tumour agents.

A flexible, direct, high yielding synthesis of 2-alkylsulfanyl estrogens from estrone has been developed. 2-Methylsulfanyl estradiol (2-MeSE2) 7 displays a similar anti-proliferative activity to the established 2-methoxyestradiol (2-MeOE2) 1, whilst its 3-O-sulfamate derivative (2-MeSE2MATE) 9 exhibits greatly enhanced anti-proliferative activity, combined with significant inhibition of steroid sulfatase, an enzyme target for the treatment of hormone-dependent tumours.

Synthesis of D-2-deoxy-myo-inositol 1,3,4,5-tetrakisphosphate from D-glucose

A route to a novel, structurally modified D-myo-inositol 1,3,4,5-tetrakisphosphate analogue, D-2-deoxy-myo-inositol 1,3,4,5-tetrakisphosphate 3, is described, involving as the key steps a selective protection of methyl α-D-glucopyranoside and subsequent catalytic Ferrier rearrangement to a deoxyinosose. Thus, methyl α-D-glucopyranoside was converted by an improved procedure into methyl 4,6-O-benzylidene-α-D-glucopyranoside 4 and thence into methyl 3-O-benzoyl-2-O-benzyl-4,6-O-benzylidene-α-D-glucopyranoside 7 without recourse to column chromatography. Compound 7 was converted into methyl 3,4-di-O-benzoyl-2-O-benzyl-6-deoxy-α-D-xylo-hex-5-enopyranoside 12 via methyl 3,4-di-O-benzoyl-2-O-benzyl-6-bromo-6-deoxy-α-D-glucopyranoside 8. Rearrangement of enol ether 12 with mercury(II) trifluoroacetate provided (2S,3R,4S,5R)-2,3-dibenzoyloxy-4-benzyloxy-5-hydroxycyclohexanone 13 and (2S,3A,4S,5S)-2,3-dibenzoyloxy-4-benzyloxy-5-hydroxycyclohexanone 14. Attempts to invert the configuration at position 5 of compound 14 were unsuccessful, but provided a number of discrete products. Reduction of compound 13 and saponification furnished L-1-O-benzyl-3-deoxy-scyll-inositol 23, which was phosphorylated and deprotected to give the target 3.

A Ca(2+)-mobilising carbohydrate-based polyphosphate: synthesis of 2-hydroxyethyl alpha-D-glucopyranoside 2',3,4-trisphosphate.

Two routes to a glucose-based mimic of the second messenger 1D-myo-inositol 1,4,5-trisphosphate related to adenophostin A are described. Fischer glycosidation of D-glucose with allyl alcohol in the presence of a strong cation-exchange resin gave a 7:3 alpha: beta-anomeric mixture of allyl glucopyranosides (5ab) from which the pure alpha anomer 5a was isolated by crystallisation. Treatment of 5ab with 1.05 equiv of dibutyltin oxide followed by 2.1 equiv of benzoyl chloride gave allyl 2,6-di-O-benzoyl-alpha-D-glucopyranoside, which was converted in 3 steps into allyl 2,6-di-O-benzyl-3,4-O-isopropylidene-alpha-D-glucopyranoside (4). Alternatively, treatment of 5a with 2.5 equiv of dibutyltin oxide followed by benzyl bromide gave allyl 2,6-di-O-benzyl-alpha-D-glucopyranoside (9) which was also converted into 4. Compound 4 was elaborated to the phosphorylation precursor 2-hydroxyethyl 2,6-di-O-benzyl-alpha-D-glucopyranoside (12) in a convenient one-pot reaction, and 12 was phosphorylated and deblocked to afford 2-hydroxyethyl alpha-D-glucopyranoside 2',3,4-trisphosphate. The 2,6-di-O-benzyl derivative 9 was converted in high yield into 2,6-di-O-benzyl-3,4-di-O-(p-methoxybenzyl)-D-glucopyranose, a useful intermediate for the synthesis of adenophostin A and related compounds.

Guanophostin A: Synthesis and evaluation of a high affinity agonist of the D-myo-inositol 1,4,5-trisphosphate receptor.

Guanophostin A, the guanosine counterpart of the inositol 1,4,5-trisphosphate receptor agonist adenophostin A, has been synthesized and is the first synthetic adenophostin A-like analogue to be equipotent to its parent in stimulating intracellular Ca2+ release; its nucleotide moiety is proposed to interact with the receptor binding core by guanine base cation-pi stacking with Arg504 and hydrogen bonding with Glu505 and interaction of the ribosyl 2'-phosphate group with the helix-dipole of alpha6.

Novel and potent 17beta-hydroxysteroid dehydrogenase type 1 inhibitors.

Structure-based drug design using the crystal structure of human 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) led to the discovery of novel, selective, and the most potent inhibitors of 17beta-HSD1 reported to date. Compounds 1 and 2 contain a side chain with an m-pyridylmethyl-amide functionality extended from the 16beta position of a steroid scaffold. A mode of binding is proposed for these inhibitors, and 2 is a steroid-based 17beta-HSD1 inhibitor with the potential for further development.

Adenophostin A and analogues modified at the adenine moiety: synthesis, conformational analysis and biological activity.

The synthesis of adenophostin A (2) and two analogues [etheno adenophostin (4) and 8-bromo adenophostin (5)] modified at the adenine moiety, is reported. A combination of NMR analysis and molecular modelling was used to compare their structures in solution and determined that they all adopt very similar conformations. The analogues were tested for their ability to mobilise Ca(2+) from DT40 cells expressing recombinant Type 1 rat Ins(1,4,5)P(3)R which reveals etheno adenophostin as a high affinity fluorescent probe of the Ins(1,4,5)P(3)R. 8-Bromo adenophostin was only slightly less potent. The biological results support our current hypothesis regarding the binding mode of adenophostin A at the Ins(1,4,5)P(3)R, i. e. that a cation-pi interaction between the base moiety and Arg 504 of the receptor in combination with H-bonding may be responsible for the high potency of adenophostin A relative to Ins(1,4,5)P(3).

Estrone sulfamates: potent inhibitors of estrone sulfatase with therapeutic potential.

Inframolecular studies of the protonation of adenophostin A: comparison with 1-D-myo-inositol 1,4,5-trisphosphate.

Adenophostin A is a glyconucleotide natural product with the highest known potency for the D-myo-inositol 1,4,5-trisphosphate receptor. Using synthetic adenophostin A we have investigated the macroscopic and microscopic protonation process of this compound by performing (31)P NMR, (1)H NMR, and potentiometric titration experiments. The logarithms of the first to the fourth stepwise protonation constants are, respectively, log K(1) = 8.48, log K(2) = 6.20, log K(3) = 4.96, and log K(4) = 3.80. The latter constant refers to the protonation equilibrium involving the N1 adenine nitrogen. From the microconstants the protonation fractions of each individual phosphate group can be calculated. Remarkably, the ionization state of the phosphates of adenophostin A at near physiological pH is very similar to those of inositol 1,4,5-trisphosphate, indicating that differences in phosphate charge cannot account for the high potency of this molecule. The analysis of the (1)H chemical shifts vs pH provided complementary conformational information. In particular, a slight "wrongway shift" of H1" can be related to the protonation of P2, thus indicating a short H1"-P2 distance. Our results are in line with a recently published model in which, however, a certain degree of constraint would keep the ribose 2'-phosphate moiety close to the glucose ring phosphates.

Inhibition of MDA-MB-231 cell cycle progression and cell proliferation by C-2-substituted oestradiol mono- and bis-3-O-sulphamates.

A natural metabolite of oestradiol (E2), 2-methoxyoestradiol (2-MeOE2), exerts both antitumour and antiangiogenic effects. 2-MeOE2 is currently in clinical trials for the treatment of a variety of cancers. We have previously shown that a number of sulphamoylated analogues of 2-MeOE2 possess enhanced potency and bioavailability with respect to 2-MeOE2. In our study, the effects of C-2-substituted E2 derivatives, with sulphamoylation at the C-3 and/or C-17 position, on ERalpha -ve MDA-MB-231 breast cancer cells were evaluated. Sulphamoylated derivatives were potent inhibitors of cell proliferation, and these effects were irreversible when compared to growth inhibitory effects induced by 2-MeOE2. Cell cycle analysis suggested that these derivatives caused cells to arrest at the G2-M phase of the cell cycle. Sulphamoylated analogues suppressed the clonogenic potential of MDA-MB-231 cells and also their growth on Matrigel culture substratum. Immunofluorescence studies showed fragmented nuclear bodies and an abnormal microtubule cytoskeleton in cells exposed to one of the potent compounds, 2-MeOE2-bis-sulphamate. In addition, these analogues induced phosphorylation of BCL-2, a protein considered to be the guardian of microtubule integrity. In each of the assays, the sulphamoylated derivatives were at least 10-fold more potent than the parent compound 2-MeOE2. In view of the enhanced potencies associated with sulphamoylated E2 derivatives in ERalpha -ve cells, these analogues should hold considerable therapeutic potential for the treatment of hormone-independent breast cancers.

Inhibition of in vitro angiogenesis by 2-methoxy- and 2-ethyl-estrogen sulfamates.

Sulfamoylation of 2-methoxyestrone (2-MeOE1) was shown previously to enhance its potency as an anti-proliferative agent against breast cancer cells. We have examined the ability of a series of 2-methoxyestradiol (2-MeOE2) and 2-ethylestradiol (2-EtE2) sulfamates to inhibit angiogenesis in vitro. 2-MeOE2 bis-sulfamate and 2-EtE2 sulfamate were potent inhibitors of human umbilical vein endothelial cell (HUVEC) proliferation with IC(50) values of 0.05 microM and 0.01 microM, respectively. A novel co-culture system, in which endothelial cells were cultured in a matrix of human dermal fibroblasts, was also used to assess the anti-angiogenic potential of these drugs. In this system endothelial cells proliferate and migrate through the culture matrix to form tubule structures. Whereas 2-MeOE2 (1.0 microM) caused a small reduction in tubule formation, both 2-MeOE2 bis-sulfamate (0.1 microM) and 2-EtE2 sulfamate (0.1 microM) almost completely abolished tubule formation. 2-MeOE2 bis-sulfamate and 2-EtE2 sulfamate both induced BCL-2 phosphorylation, p53 protein expression and apoptosis in HUVECs. Microarray analysis of a limited number of genes known to be involved in the angiogenic process did not show any gross changes in cells treated with the 2-substituted estrogens. The sulfamoylated derivatives of 2-MeOE2 and 2-EtE2 are potent inhibitors of in vitro angiogenesis and both compounds should have therapeutic potential.

Steroid sulphatase: expression, isolation and inhibition for active-site identification studies.

Steroid sulphatase, which can hydrolyse 3-hydroxysteroid sulphates, has important roles in several physiological and pathological processes. A number of steroid sulphatase inhibitors have now been developed, of which the most potent to date is oestrone-3-O-sulphamate (EMATE). This inhibitor inactivates steroid sulphatase in an irreversible, time- and concentration-dependent manner. In order to be able to use a radiolabelled derivative of EMATE to study the active site, it will be essential to prepare the steroid sulphatase in a pure form. For this, attempts have been made to express the protein, using the steroid sulphatase cDNA, in the pGEX2T expression system and also to express a mutant form of the protein, in which the putative membrane-spanning domain was deleted, in CHO cells. In addition, a soluble steroid sulphatase has been identified from the snail Helix pomatia. This steroid sulphatase is inhibited by EMATE in an irreversible manner, similar to the human steroid sulphatase and appears to possess a histidine residue at its active site. The expression and/or isolation of a steroid sulphatase, in conjunction with the use of a radiolabelled derivative of EMATE should allow important new information about the active site of this enzyme and the mechanism of its inactivation to be obtained.

Total synthesis of nucleobase-modified adenophostin A mimics.

The adenophostins exhibit approximately 10-100 times higher receptor binding and Ca2+ mobilising potencies in comparison with the natural second messenger D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. Despite many synthetic attempts to determine the minimal structural requirement for this unusual behaviour of the adenophostins, few related simplified analogues displaying higher activity than that of Ins(1,4,5)P3 have been reported. However, biological evaluation of such analogues has revealed that one of the key factors for the enhanced biological activity is the adenine moiety. To further understand the effect that the adenine base has upon the activity of the adenophostins, congeners in which this functionality is replaced by uracil, benzimidazole, 2-methoxynaphthalene, 4-methylanisole and 4-methylnaphthalene using the common intermediate 1,2-di-O-acetyl-5-O-benzyl-3-O-(3,4-di-O-acetyl-2,6-di-O-benzyl-alpha-D-glucopyranosyl)-ribofuranose have been synthesised using a base replacement strategy. The synthesis of the uracil and benzimidazole analogues was achieved using the Vorbrüggen condensation procedure. The 1'-C-glycosidic analogues were prepared using Friedel-Crafts type C-aryl glycosidation reactions. Phosphate groups were introduced using the phosphoramidite method with subsequent removal of all-benzyl protecting groups by catalytic hydrogenation or catalytic hydrogen transfer. Apart from one analogue with an alpha-glycosidic linkage all compounds were more potent than Ins(1,4,5)P3 and most tended more towards adenophostin in activity. These analogues will be valuable tools to unravel the role that the adenine moiety plays in the potent activity of the adenophostins and demonstrate that this strategy is effective at producing highly potent ligands.

D-myo-inositol 1,4,5-trisphosphate analogues modified at the 3-position inhibit phosphatidylinositol 3-kinase.

Several natural and unnatural inositol phosphates and analogues were analyzed for their ability to inhibit the in vitro phosphatidylinositol 3-kinase (PI 3-kinase) activity immunoprecipitated from a leukemic T cell line by a p85 monoclonal antibody. A 3-position ring-modified analogue of D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), L-chiro-inositol 2,3,5-trisphosphate (L-chiro-Ins(2,3,5)P3) and its phosphorothioate analogue, L-chiro-inositol 2,3,5-trisphosphorothioate, as well as the analogue benzene 1,2,4-trisphosphate induced reversible inhibition of PI 3-kinase activity, which correlated with decreased Vmax but unchanged Km values for PI 3-kinase. Other inositol phosphates, including D- and L-Ins(1,4,5)P3, D-myo-inositol 1,3,4,5-tetrakisphosphate, the enantiomers of myo-inositol 1,3,4-trisphosphate, DL-myo-inositol 1,4,6-trisphosphate (DL-Ins(1,4,6)P3), and DL-scyllo-inositol 1,2,4-trisphosphate (DL-scyllo-Ins(1,2,4)P3), did not inhibit PI 3-kinase activity under identical conditions. L-chiro-Ins(2,3,5)P3 closely resembles Ins(1,4,5)P3 and D-Ins(1,4,6)P3 except for a difference in the orientation of a single hydroxyl group at either the equivalent 3-OH or 2-OH position of Ins(1,4,5)P3, respectively. Similarly, L-chiro-Ins(2,3,5)P3 resembles D-scyllo-Ins(1,2,4)P3, but has a different orientation of both the equivalent 3-OH and 2-OH positions. Since Ins(1,4,5)P3, DL-Ins(1,4,6)P3, and DL-scyllo-Ins(1,2,4)P3 did not inhibit PI 3-kinase activity, this suggests that the orientation of the two hydroxyl groups at the 2- and 3-positions plays a pivotal role in the inhibitory action of inositol phosphate analogues on PI 3-kinase activity. Thus, inositol phosphate analogues inter alia are shown for the first time to inhibit PI 3-kinase and may be useful tools for determining the function of PI 3-kinase and its substrate binding specificities.

Synthesis of C5-substituted AE-bicyclic analogues of lycoctonine, inuline and methyllycaconitine

We have prepared C5-substituted AE-bicyclic analogues of norditerpenoid alkaloids lycoctonine, inuline and methyllycaconitine via an acetylide anion addition strategy. Using two acetylide anions, we have regioselectively linked two cyclic ketones to acetylene.

Synthesis of novel unsaturated AE-bicyclic analogues of lycoctonine, inuline and methyllycaconitine: With olefinic J = 13.5 Hz, but still cis

We have synthesised unsaturated AE-bicyclic analogues of lycoctonine class norditerpenoid alkaloids by acetylide addition and regiochemically controlled reductions. Reduction of a substituted propargylic alcohol with hydrogen gas (poisoned Pd catalyst) gave an alkene with vicinal J = 13.5 Hz. This was shown to be of Z-geometry by unambiguously preparing the corresponding E-alkene (J = 15.4 Hz).