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Pharmacokinetic properties of our first-generation HIF-2α antagonist PT2385, including modest solubility, resulted in a high recommended phase 2 dose (RP2D) of 800 mg BID and motivated the pursuit of novel scaffolds which could improve solubility and formulation parameters with the goal of improved pharmacokinetics. Herein we disclose our successful efforts to identify such HIF-2α antagonists through an optimization strategy characterized by: (1) increasing the fraction of sp3 hybridized carbons (Fsp3), (2) replacing the aromatic portion of the indane core with pyridine heterocycles, and (3) improving a putative Olp → π*Ar interaction, an underutilized electrostatic contact in medicinal chemistry. These efforts emphasize the importance of employing multiple strategies in parameter optimization. In isolation, modifications to areas (1) and (2) improved solubility, but with the compromise of reduced potency. In area (3), understanding the importance of an Olp → π*Ar interaction, as documented through a wealth of crystal structures and retrospective calculations, proved essential in guiding SAR and identifying the trifluoromethyl group as a suitable replacement of the sulfone. Only by combining these three strategies could inhibitors with substantially improved solubility and comparable potency be discovered. Finally, the overall improvement in pharmacokinetic properties of the newly identified inhibitors is highlighted through a battery of ADME and in vivo data, including use of pharmacodynamic biomarkers indicative of HIF-2α antagonism.

Supplementary method includes detailed experimental procedure for the synthesis of PT2385. Supplementary Figures 1-7 - Lack of cytotoxicity of PT2385 in cultured 786-O and A498 cells (1); PT2385 pharmacokinetics in CD-1 mice (2); Inhibition of HIF-2� gene expression and circulating hVEGFa in A498 mouse xenograft model after treatment with PT2385 (3); HIF-2� mRNA and protein levels in 786-O cells in vitro after treatment with PT2385 (4); Levels of HIF-1� and HIF-2� in patient-derived xenograft tumors (5); Body weight of mice in efficacy studies treated with either vehicle, PT2385 or sunitinib (6); Binding of PT2385 to rat HIF-2� as determined by ITC and inhibition of mouse kidney EPO gene expression with PT2385 treatment (7).

More than 90% of clear cell renal cell carcinomas (ccRCC) exhibit inactivation of the von Hippel–Lindau (pVHL) tumor suppressor, establishing it as the major underlying cause of this malignancy. pVHL inactivation results in stabilization of the hypoxia-inducible transcription factors, HIF1α and HIF2α, leading to expression of a genetic program essential for the initiation and progression of ccRCC. Herein, we describe the potent, selective, and orally active small-molecule inhibitor PT2385 as a specific antagonist of HIF2α that allosterically blocks its dimerization with the HIF1α/2α transcriptional dimerization partner ARNT/HIF1β. PT2385 inhibited the expression of HIF2α-dependent genes, including VEGF-A, PAI-1, and cyclin D1 in ccRCC cell lines and tumor xenografts. Treatment of tumor-bearing mice with PT2385 caused dramatic tumor regressions, validating HIF2α as a pivotal oncogenic driver in ccRCC. Notably, unlike other anticancer agents that inhibit VEGF receptor signaling, PT2385 exhibited no adverse effect on cardiovascular performance. Thus, PT2385 represents a novel class of therapeutics for the treatment of RCC with potent preclincal efficacy as well as improved tolerability relative to current agents that target the VEGF pathway. Cancer Res; 76(18); 5491–500. ©2016 AACR.

HIF-2α, a member of the HIF family of transcription factors, is a key oncogenic driver in cancers such as clear cell renal cell carcinoma (ccRCC). A signature feature of these cancers is the overaccumulation of HIF-2α protein, often by inactivation of the E3 ligase VHL (von Hippel–Lindau). Herein we disclose our structure based drug design (SBDD) approach that culminated in the identification of PT2385, the first HIF-2α antagonist to enter clinical trials. Highlights include the use of a putative n → π*Ar interaction to guide early analog design, the conformational restriction of an essential hydroxyl moiety, and the remarkable impact of fluorination near the hydroxyl group. Evaluation of select compounds from two structural classes in a sequence of PK/PD, efficacy, PK, and metabolite profiling identified 10i (PT2385, luciferase EC50 = 27 nM) as the clinical candidate. Finally, a retrospective crystallographic analysis describes the structural perturbations necessary for efficient antagonism.

Clear cell renal cell carcinoma (ccRCC) is characterized by inactivation of the von Hippel-Lindau tumour suppressor gene (VHL). Because no other gene is mutated as frequently in ccRCC and VHL mutations are truncal, VHL inactivation is regarded as the governing event. VHL loss activates the HIF-2 transcription factor, and constitutive HIF-2 activity restores tumorigenesis in VHL-reconstituted ccRCC cells. HIF-2 has been implicated in angiogenesis and multiple other processes, but angiogenesis is the main target of drugs such as the tyrosine kinase inhibitor sunitinib. HIF-2 has been regarded as undruggable. Here we use a tumourgraft/patient-derived xenograft platform to evaluate PT2399, a selective HIF-2 antagonist that was identified using a structure-based design approach. PT2399 dissociated HIF-2 (an obligatory heterodimer of HIF-2α-HIF-1β) in human ccRCC cells and suppressed tumorigenesis in 56% (10 out of 18) of such lines. PT2399 had greater activity than sunitinib, was active in sunitinib-progressing tumours, and was better tolerated. Unexpectedly, some VHL-mutant ccRCCs were resistant to PT2399. Resistance occurred despite HIF-2 dissociation in tumours and evidence of Hif-2 inhibition in the mouse, as determined by suppression of circulating erythropoietin, a HIF-2 target and possible pharmacodynamic marker. We identified a HIF-2-dependent gene signature in sensitive tumours. Gene expression was largely unaffected by PT2399 in resistant tumours, illustrating the specificity of the drug. Sensitive tumours exhibited a distinguishing gene expression signature and generally higher levels of HIF-2α. Prolonged PT2399 treatment led to resistance. We identified binding site and second site suppressor mutations in HIF-2α and HIF-1β, respectively. Both mutations preserved HIF-2 dimers despite treatment with PT2399. Finally, an extensively pretreated patient whose tumour had given rise to a sensitive tumourgraft showed disease control for more than 11 months when treated with a close analogue of PT2399, PT2385. We validate HIF-2 as a target in ccRCC, show that some ccRCCs are HIF-2 independent, and set the stage for biomarker-driven clinical trials.

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) suppress normal hematopoietic activity in part by enabling a pathogenic inflammatory milieu in the bone marrow. In this report, we show that elevation of angiopoietin-1 in myelodysplastic CD34+ stem-like cells is associated with higher risk disease and reduced overall survival in MDS and AML patients. Increased angiopoietin-1 expression was associated with a transcriptomic signature similar to known MDS/AML stem-like cell profiles. In seeking a small-molecule inhibitor of this pathway, we discovered and validated pexmetinib (ARRY-614), an inhibitor of the angiopoietin-1 receptor Tie-2, which was also found to inhibit the proinflammatory kinase p38 MAPK (which is overactivated in MDS). Pexmetinib inhibited leukemic proliferation, prevented activation of downstream effector kinases, and abrogated the effects of TNFα on healthy hematopoietic stem cells. Notably, treatment of primary MDS specimens with this compound stimulated hematopoiesis. Our results provide preclinical proof of concept for pexmetinib as a Tie-2/p38 MAPK dual inhibitor applicable to the treatment of MDS/AML. Cancer Res; 76(16); 4841–9. ©2016 AACR.

HIF-2α, a member of the HIF family of transcription factors, is a key oncogenic driver in cancers such as clear cell renal cell carcinoma (ccRCC). A signature feature of these cancers is the overaccumulation of HIF-2α protein, often by inactivation of the E3 ligase VHL (von Hippel-Lindau). Herein we disclose our structure based drug design (SBDD) approach that culminated in the identification of PT2385, the first HIF-2α antagonist to enter clinical trials. Highlights include the use of a putative n → π*

The transcription factor HIF-2, an important driver of clear cell renal cell carcinoma, has been called 'undruggable'. However, in this issue of Nature, two groups report on the development and testing of a novel HIF-2 inhibitor, termed PT2399. William Kaelin and colleagues show that PT2399 causes tumour regression in preclinical mouse models of primary and metastatic pVHL-defective clear cell renal cell carcinoma. James Brugarolas and colleagues tested the compound in mice with tumour grafts generated from human renal cell cancers. PT2399 decreased tumour growth in 10 out of 18 cell lines and was well tolerated. The authors identify potential markers of sensitivity and provide initial characterization of the effects and mechanisms of resistance acquisition in vivo. Both groups report variable sensitivity to PT2399 in some pVHL-defective cell lines, highlighting a need for predictive biomarkers to be developed for use of this approach in the clinic.

More than 90% of clear cell renal cell carcinomas (ccRCC) exhibit inactivation of the von Hippel–Lindau (pVHL) tumor suppressor, establishing it as the major underlying cause of this malignancy. pVHL inactivation results in stabilization of the hypoxia-inducible transcription factors, HIF1α and HIF2α, leading to expression of a genetic program essential for the initiation and progression of ccRCC. Herein, we describe the potent, selective, and orally active small-molecule inhibitor PT2385 as a specific antagonist of HIF2α that allosterically blocks its dimerization with the HIF1α/2α transcriptional dimerization partner ARNT/HIF1β. PT2385 inhibited the expression of HIF2α-dependent genes, including VEGF-A, PAI-1, and cyclin D1 in ccRCC cell lines and tumor xenografts. Treatment of tumor-bearing mice with PT2385 caused dramatic tumor regressions, validating HIF2α as a pivotal oncogenic driver in ccRCC. Notably, unlike other anticancer agents that inhibit VEGF receptor signaling, PT2385 exhibited no adverse effect on cardiovascular performance. Thus, PT2385 represents a novel class of therapeutics for the treatment of RCC with potent preclincal efficacy as well as improved tolerability relative to current agents that target the VEGF pathway. Cancer Res; 76(18); 5491–500. ©2016 AACR.

Human lung tryptase, a homotetrameric serine protease unique to mast cell secretory granules, has been implicated in the pathogenesis of asthma. A hypothesis that tethered symmetrical inhibitors might bridge two adjacent active sites was explored via a rationally designed series of bisbenzamidines. These compounds demonstrated a remarkable distanced-defined structure–activity relationship against human tryptase with one series possessing subnanomolar potencies. Additional evidence supporting the concept of active-site bridging is also presented.

UK-78,282, a novel piperidine blocker of the T lymphocyte voltage-gated K+ channel, Kv1.3, was discovered by screening a large compound file using a high-throughput 86Rb efflux assay. This compound blocks Kv1.3 with a IC50 of ∼200 nM and 1 : 1 stoichiometry. A closely related compound, CP-190,325, containing a benzyl moiety in place of the benzhydryl in UK-78,282, is significantly less potent. Three lines of evidence indicate that UK-78,282 inhibits Kv1.3 in a use-dependent manner by preferentially blocking and binding to the C-type inactivated state of the channel. Increasing the fraction of inactivated channels by holding the membrane potential at −50 mV enhances the channel's sensitivity to UK-78,282. Decreasing the number of inactivated channels by exposure to ∼160 mM external K+ decreases the sensitivity to UK-78,282. Mutations that alter the rate of C-type inactivation also change the channel's sensitivity to UK-78,282 and there is a direct correlation between τh and IC50 values. Competition experiments suggest that UK-78,282 binds to residues at the inner surface of the channel overlapping the site of action of verapamil. Internal tetraethylammonium and external charybdotoxin do not compete UK-78,282's action on the channel. UK-78,282 displays marked selectivity for Kv1.3 over several other closely related K+ channels, the only exception being the rapidly inactivating voltage-gated K+ channel, Kv1.4. UK-78,282 effectively suppresses human T-lymphocyte activation. British Journal of Pharmacology (1999) 126, 1707–1716; doi:10.1038/sj.bjp.0702480

The in silico construction of a PDGFRβ kinase homology model and ensuing medicinal chemistry guided by molecular modeling, led to the identification of potent, small molecule inhibitors of PDGFR. Subsequent exploration of structure–activity relationships (SAR) led to the incorporation of a constrained secondary amine to enhance selectivity. Further refinements led to the integration of a fluorine substituted piperidine, which resulted in significant reduction of P-glycoprotein (Pgp) mediated efflux and improved bioavailability. Compound 28 displayed oral exposure in rodents and had a pronounced effect in a pharmacokinetic–pharmacodynamic (PKPD) assay.

A hallmark of Alzheimer's disease is the brain deposition of amyloid beta (Aβ), a peptide of 36-43 amino acids that is likely a primary driver of neurodegeneration. Aβ is produced by the sequential cleavage of APP by BACE1 and γ-secretase; therefore, inhibition of BACE1 represents an attractive therapeutic target to slow or prevent Alzheimer's disease. Herein we describe BACE1 inhibitors with limited molecular flexibility and molecular weight that decrease CSF Aβ in vivo, despite efflux. Starting with spirocycle 1a, we explore structure-activity relationships of core changes, P3 moieties, and Asp binding functional groups in order to optimize BACE1 affinity, cathepsin D selectivity, and blood-brain barrier (BBB) penetration. Using wild type guinea pig and rat, we demonstrate a PK/PD relationship between free drug concentrations in the brain and CSF Aβ lowering. Optimization of brain exposure led to the discovery of (R)-50 which reduced CSF Aβ in rodents and in monkey.

Modification of the N-carboxyalkylamine 3 by independent replacement of the P1′ NH group for CH2 and introduction of P1′ gem-cyclohexyl substitution affords compounds 5 and 6a which retain appreciable activity against MMP-1 (IC50s = 0.023 μM and 0.09 μM, respectively). The glutaramide 7a which incorporates both these structural changes also retains potent activity (IC50 = 0.038 μM).

The architecture of the pore-region of a voltage-gated K+ channel, Kv1.3, was probed using four high affinity scorpion toxins as molecular calipers. We established the structural relatedness of these toxins by solving the structures of kaliotoxin and margatoxin and comparing them with the published structure of charybdotoxin; a homology model of noxiustoxin was then developed. Complementary mutagenesis of Kv1.3 and these toxins, combined with electrostatic compliance and thermodynamic mutant cycle analyses, allowed us to identify multiple toxin-channel interactions. Our analyses reveal the existence of a shallow vestibule at the external entrance to the pore. This vestibule is approximately 28-32 A wide at its outer margin, approximately 28-34 A wide at its base, and approximately 4-8 A deep. The pore is 9-14 A wide at its external entrance and tapers to a width of 4-5 A at a depth of approximately 5-7 A from the vestibule. This structural information should directly aid in developing topological models of the pores of related ion channels and facilitate therapeutic drug design.

Beckmann rearrangement of erythromycin A 9(E)-oxime with toluenesulfonyl chloride in ethyl ether at −45°C generates 9,11-imino ether IV which leads to azithromycin. The 9,11-imino ether can also be readily obtained from isomerization of its isomer 6,9-imino ether III.

The synthesis and SAR of a series of 1-azabicyclo[3.2.2] analogues of the nonpeptide substance P antagonist CP-96,345 are described. The results demonstrate the sensitivity of the substance P receptor toward alterations in the nuclear structure of CP-96,345.

A new series of thiazolidine-2,4-diones was obtained by replacing the ether function of englitazone with various functional groups, i.e., a ketone, alcohol, or olefin moiety. These compounds lower blood glucose levels in the genetically obese and insulin-resistant ob/ob mouse. Appending an oxazole-based group at the terminus of the chain provided highly potent compounds.

A new series of thiazolidine-2,4-diones was obtained by replacing the ether function of englitazone with various functional groups, i.e., a ketone, alcohol, or olefin moiety. These compounds lower blood glucose levels in the genetically obese and insulin-resistant ob/ob mouse. Appending an oxazole-based group at the terminus of the chain provided highly potent compounds.

With computer modeling, an initial three-component pharmacophore for specific 5-HT3 receptor ligands ICS-205-930 (1), ondansetron (2), zacopride (3), and 3-[2-(guanidinylmethyl)-4-thiazolyl]indol (4) has been identified. Two parts represent electrostatic interactions, one as a hydrogen-bond-donating interaction and the other as a hydrogen-bond-accepting interaction. The third part is represented by a plane in which the lipophilic aromatic groups align. The generation of the pharmacophore relies on the interactions of these ligands with probe atoms representative of a possible hydrogen-bond donor or hydrogen-bond acceptor within the receptor. A carboxylate oxygen was used as a hydrogen-bond-accepting probe and a serine-like hydroxyl was utilized as a hydrogen-bond-donating probe.

Hypoxia-inducible factors (HIFs), including HIF-1α and HIF-2α, are transcription factors that mediate cellular response to changes of oxygen supply. These proteins become stabilized under hypoxia and subsequently activate the expression of genes to facilitate cell survival and proliferation. HIF proteins are activated in many types of cancers due to the tumor hypoxic microenvironment and have been implicated in cancer initiation, progression and metastasis. The oncogenic role of HIF-2α is pertinent in clear cell renal carcinoma (ccRCC). In the majority of ccRCC tumors, the von Hippel-Lindau protein (VHL) that targets HIF-2α for degradation is inactivated, leading to the accumulation of HIF-2α and the activation of genes that drive kidney cancer tumorigenesis. We have identified small molecules that bind to the PAS-B domain of HIF-2α protein and block it's dimerization with ARNT (aryl hydrocarbon receptor nuclear translocator, HIF-1β), a prerequisite for its transcriptional activities. Specifically, we describe PT2385, a selective, orally active HIF-2α antagonist with potent anti-cancer activity in mouse models of ccRCC. PT2385 is currently under evaluation in Phase I clinical trials for the treatment of ccRCC. Citation Format: Eli M. Wallace, Zhaodan Cao, Tzuling Cheng, Robert Czerwinski, Darryl D. Dixon, Xinlin Du, Barry Goggin, Jonas Grina, Megan Halfmann, Guangzhou Han, Heli Huang, John A. Josey, Melissa A. Maddie, Sarah Olive, James Rizzi, Stephen T. Schlachter, Hui-Ling Tan, Bin Wang, Keshi Wang, Paul M. Wehn, Shanhai Xie, Rui Xu, Hanbiao Yang. PT2385: First-in-class HIF-2α antagonist for the treatment of renal cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr DDT01-01. doi:10.1158/1538-7445.AM2015-DDT01-01

Several docking programs are now available that can reproduce the bound conformation of a ligand in an active site, for a wide variety of experimentally determined complexes. However, these programs generally perform less well at ranking multiple possible ligands in one site. Since accurate identification of potential ligands is a prerequisite for many aspects of structure-based drug design, this is a serious limitation. We have tested the ability of two docking programs, FlexX and Gold, to match ligands and active sites for multiple complexes. We show that none of the docking scores from either program are able to match consistently ligands and active sites in our tests. We propose a simple statistical correction, the multiple active site correction (MASC), which greatly ameliorates this problem. We have also tested the correction method against an extended set of 63 cocrystals and in a virtual screening experiment. In all cases, MASC significantly improves the results of the docking experiments.

A highly conserved motif, GYGD, contributes to the formation of the ion selectivity filter in voltage-gated K+ channels and is thought to interact with the scorpion toxin residue, Lys27. By probing the pore of the Kv1.3 channel with synthetic kaliotoxin-Lys27 mutants, each containing a non-natural lysine analog of a different length, and using mutant cycle analysis, we determined the spatial locations of Tyr400 and Asp402 in the GYGD motif, relative to His404 located at the base of the outer vestibule. Our data indicate that the terminal amines of the shorter Lys27 analogs lie close to His404 and to Asp402, while Lys27 itself interacts with Tyr400. Based on these data, we developed a molecular model of this region of the channel. The junction between the outer vestibule and the pore is defined by a ring ( approximately 8-9-A diameter) formed from alternating Asp402 and His404 residues. Tyr400 lies 4-6 A deeper into the pore, and its interaction with kaliotoxin-Lys27 is in competition with K+ ions. Studies with dimeric Kv1.3 constructs suggest that two Tyr400 residues in the tetramer are sufficient to bind K+ ions. Thus, at least part of the K+ channel signature sequence extends into a shallow trough at the center of a wide external vestibule.

Increasing evidence suggests that interactions between tumor cells, stromal cells, macrophages and the extracellular matrix are pivotal to the processes of tumorigenesis, metastasis, and neovascularization. Macrophages within the tumor microenvironment are thought to facilitate cancer progression, making them intriguing targets for therapy. Colony stimulating factor 1 (CSF-1) and its receptor, cFMS, play a central role in the development of mononuclear phagocytes, recruitment of macrophages to tumors, and differentiation and function of osteoclasts. We have developed an orally active, selective small-molecule cFMS inhibitor for cFMS. This molecule inhibits cFMS cellular activity (IC50 = 9 nM) in vitro and inhibits cFMS phosphorylation in a transfected cell line grown in nude mice (ED50 = 3 mg/kg). Our compound also inhibits CSF-1-mediated osteoclast differentiation and function (IC50 values of = 4 nM and 58 nM, respectively). To further explore the potential of our selective inhibitor for the treatment of cancer, we evaluated anti-tumor activity in several preclinical models. We first explored the effect on the murine ovarian cancer cell line, ID8. ID8 cells injected intraperitoneally into nude mice form multiple peritoneal tumor deposits and abundant ascites. Macrophage infiltration in the ID8 ascites was markedly lowered in mice treated with a cFMS inhibitor. Using MCF-7, a human breast adenocarcinoma cell line that has been shown to produce M-CSF, a daily oral dose with 100 mg/kg of our inhibitor for 21 days significantly reduced tumor growth and was accompanied by a marked reduction in tumor-associated macrophages. These findings support the potential of a selective inhibitor of cFMS to favorably impact human cancers by modulating tumor-associated macrophage functions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 551. doi:10.1158/1538-7445.AM2011-551

A novel structural class of highly potent and selective 5-HT3 receptor antagonists is described. The compounds in this new series contain a thiazole moiety linking an aromatic group and a nitrogen-containing basic region; the thiazole group appears to be acting as a carbonyl bioisostere in this system. An optimized member of this series, 4-(2-methoxyphenyl)-2-[[4(5)-methyl-5(4)-imidazolyl]methyl]thiazole (5), exhibits oral activity in the Bezold-Jarisch reflex paradigm comparable to or better than the standard agents ondansetron (1) and ICS-205-930 (2). Several of the structure-activity relationships are rationalized in terms of a computer pharmacophore model for 5-HT3 receptor binding.

Sorbinil (1), a spirocyclic hydantoin, is a potent inhibitor of the enzyme aldose reductase. Simulation of the rigid spirocyclic ring orientation found in sorbinil was achieved with nonspirocyclic 5-[5'-chloro-2'-(alkylsulfonyl)-phenyl]hydantoins and 5-[5'-chloro-2'-[(N-alkylamino)sulfonyl]phenyl]hydantoins. The 2'-substituent (SO2R) was sufficiently large to hinder rotation of the hydantoin ring, forcing an orientation similar to that of a spirocyclic hydantoin. Calculated conformational preference, X-ray data, and inhibitory IC50 values for these nonspirocyclic 2'-substituted (SO2R) phenylhydantoins are in accord with what is expected for spirocyclic hydantoins and comparable to those of sorbinil.

Sorbinil (1), a spirocyclic hydantoin, is a potent inhibitor of the enzyme aldose reductase. Simulation of the rigid spirocyclic ring orientation found in sorbinil was achieved with nonspirocyclic 5-[5'-chloro-2'-(alkylsulfonyl)-phenyl]hydantoins and 5-[5'-chloro-2'-[(N-alkylamino)sulfonyl]phenyl]hydantoins. The 2'-substituent (SO2R) was sufficiently large to hinder rotation of the hydantoin ring, forcing an orientation similar to that of a spirocyclic hydantoin. Calculated conformational preference, X-ray data, and inhibitory IC50 values for these nonspirocyclic 2'-substituted (SO2R) phenylhydantoins are in accord with what is expected for spirocyclic hydantoins and comparable to those of sorbinil.

A stereospecific synthesis of aklavinone (2) in 16 steps from 5-methoxy- 1-tetralone with an overall yield of 6.5% is described. Regiospecific control in forming the BCD-ring chromophore was accomplished by coupling of a preformed bicyclic AB-ring aldehyde (29) with a nucleophilic D-ring carboxamide (3), with stepwise bond formation as illustrated in equation 2. The coupled product was subsequently transformed into (±)-aklavinone. An enantioselective synthesis of aklavinone was achieved in 53%. e.e. using the procedure of Sharpless for the asymmetric epoxidation of allylic alcohol 2413