Total synthesis of GEX1Q1, assignment of C-5 stereoconfiguration and evaluation of spliceosome inhibitory activity.

An enantioselective total synthesis of GEX1Q1 has been accomplished in a convergent manner. The C-5 asymmetric center has now been assigned through synthesis. GEX1Q1 displayed slightly better spliceosome inhibitory activity over its C-5 epimer. The salient features of this synthesis include an asymmetric hetero-Diels-Alder reaction to construct the tetrahydropyran ring and a Suzuki cross-coupling to assemble the key segments

Synthesis of beta -amino-alpha -hydroxy esters and beta -amino-alpha -azido ester by Sharpless asymmetric aminohydroxylation, byproducts analysis

Synthesis of enantiomerically pure beta -amino-alpha -hydroxy esters, e.g., I, and beta -amino-alpha -azido ester using Sharpless AA as a key step is described. A side reaction, the oxidn. of the beta -hydroxy-alpha -amino ester into the alpha ,alpha -di-tert-butyloxycarbamoyl-beta -ketoester under AA conditions, is also documented. [on SciFinder (R)

Total Synthesis of GEX1Q1, Assignment of C‑5 Stereoconfiguration and Evaluation of Spliceosome Inhibitory Activity

An enantioselective total synthesis of GEX1Q1 has been accomplished in a convergent manner. The C-5 asymmetric center has now been assigned through synthesis. GEX1Q1 displayed slightly better spliceosome inhibitory activity over its C-5 epimer. The salient features of this synthesis include an asymmetric hetero-Diels–Alder reaction to construct the tetrahydropyran ring and a Suzuki cross-coupling to assemble the key segments

Design, synthesis and in vitro splicing inhibition of desmethyl and carba-derivatives of herboxidiene.

Herboxidiene is a potent inhibitor of spliceosomes. It exhibits excellent anticancer activity against multiple human cancer cell lines. Herein, we describe an enantioselective synthesis of a desmethyl derivative and the corresponding carba-derivatives of herboxidiene. The synthesis involved Suzuki coupling of a vinyl iodide with boronate as the key reaction. For the synthesis of carba-derivatives, the corresponding optically active cyclohexane-1,3-dicarbonyl derivatives were synthesized using an enantioselective desymmetrization of meso-anhydride. The biological properties of these derivatives were evaluated in an in vitro splicing assay

Design, synthesis and in vitro splicing inhibition of desmethyl and carba-derivatives of herboxidiene.

Herboxidiene is a potent inhibitor of spliceosomes. It exhibits excellent anticancer activity against multiple human cancer cell lines. Herein, we describe an enantioselective synthesis of a desmethyl derivative and the corresponding carba-derivatives of herboxidiene. The synthesis involved Suzuki coupling of a vinyl iodide with boronate as the key reaction. For the synthesis of carba-derivatives, the corresponding optically active cyclohexane-1,3-dicarbonyl derivatives were synthesized using an enantioselective desymmetrization of meso-anhydride. The biological properties of these derivatives were evaluated in an in vitro splicing assay

Design and synthesis of simple macrocycles active against vancomycin-resistant Enterococci (VRE)

16-Membered meta,para-cyclophanes mimicking the vancomycin binding pocket (D-O-E ring) were designed and synthesized. The structural key features of these biaryl ether contg. macrocycles are (1) the presence of beta -amino-alpha -hydroxy acid or alpha ,beta -diamino acid as the C-terminal component of the cyclopeptide, and (2) the presence of a hydrophobic chain or lipidated aminoglucose at the appropriate position. Cycloetherification by an intramol. nucleophilic arom. substitution reaction (SNAr) is used as the key step for the construction of the macrocycle. The atropselectivity of this ring-closure reaction is found to be sensitive to the peptide backbone and chemoselective cyclization (phenol vs. primary amine) is achievable. Glycosylation of phenol was realized with freshly prepd. 3,4,6-tri-O-acetyl-2-N-lauroyl-2-amino-2-deoxy-alpha -D-glucopyranosyl bromide under phase-transfer conditions. Min. inhibitory concns. for all of the derivs. are measured by using a std. microdilution assay, and potent bioactivities against both sensitive and resistant strains are found for some of these compds. [MIC (min. inhibitory concn.) = 4 micro g mL-1 against VRE]. From these preliminary SAR studies, it was anticipated that both the presence of a hydrophobic substituent and an appropriate structure of the macrocycle were required for this series of compds. to be active against VRE. [on SciFinder (R)

Identification of synthetic compounds active against VRE: the role of the lipidated aminoglucose and the structure of glycopeptide binding pocket

A modified vancomycin binding pocket (D-O-E ring) incorporating an alpha -hydroxy-beta -amino acid at the AA4 position is designed and synthesized. Some of these compds. display potent bioactivities against both sensitive- and resistant-strains (8 micro g/mL against VREF). Both the lipidated aminoglucose and the structure of the 16-membered macrocycle are found to be important for the anti-VRE activities. The polyamine appendage at the C-terminal, on the other hand, improved the activity against vancomycin-sensitive strains. [on SciFinder (R)

Coherence between cellular responses and in vitro splicing inhibition for the anti-tumor drug pladienolide B and its analogs.

Pladienolide B (PB) is a potent cancer cell growth inhibitor that targets the SF3B1 subunit of the spliceosome. There is considerable interest in the compound as a potential chemotherapeutic, as well as a tool to study SF3B1 function in splicing and cancer development. The molecular structure of PB, a bacterial natural product, contains a 12-member macrolide ring with an extended epoxide-containing side chain. Using a novel concise enantioselective synthesis, we created a series of PB structural analogs and the structurally related compound herboxidiene. We show that two methyl groups in the PB side chain, as well as a feature of the macrolide ring shared with herboxidiene, are required for splicing inhibition in vitro. Unexpectedly, we find that the epoxy group contributes only modestly to PB potency and is not absolutely necessary for activity. The orientations of at least two chiral centers off the macrolide ring have no effect on PB activity. Importantly, the ability of analogs to inhibit splicing in vitro directly correlated with their effects in a series of cellular assays. Those effects likely arise from inhibition of some, but not all, endogenous splicing events in cells, as previously reported for the structurally distinct SF3B1 inhibitor spliceostatin A. Together, our data support the idea that the impact of PB on cells is derived from its ability to impair the function of SF3B1 in splicing and also demonstrate that simplification of the PB scaffold is feasible

Coherence between cellular responses and in vitro splicing inhibition for the anti-tumor drug pladienolide B and its analogs.

Pladienolide B (PB) is a potent cancer cell growth inhibitor that targets the SF3B1 subunit of the spliceosome. There is considerable interest in the compound as a potential chemotherapeutic, as well as a tool to study SF3B1 function in splicing and cancer development. The molecular structure of PB, a bacterial natural product, contains a 12-member macrolide ring with an extended epoxide-containing side chain. Using a novel concise enantioselective synthesis, we created a series of PB structural analogs and the structurally related compound herboxidiene. We show that two methyl groups in the PB side chain, as well as a feature of the macrolide ring shared with herboxidiene, are required for splicing inhibition in vitro. Unexpectedly, we find that the epoxy group contributes only modestly to PB potency and is not absolutely necessary for activity. The orientations of at least two chiral centers off the macrolide ring have no effect on PB activity. Importantly, the ability of analogs to inhibit splicing in vitro directly correlated with their effects in a series of cellular assays. Those effects likely arise from inhibition of some, but not all, endogenous splicing events in cells, as previously reported for the structurally distinct SF3B1 inhibitor spliceostatin A. Together, our data support the idea that the impact of PB on cells is derived from its ability to impair the function of SF3B1 in splicing and also demonstrate that simplification of the PB scaffold is feasible