Highly efficient total synthesis of Δ12-PGJ2, 15-deoxy-Δ12,14-PGJ2, and their analogues

Development of a new approach for the synthesis of (+)-15-deoxy-Δ12,14-prostaglandin J2 methyl ester based on the [2+2]-cycloadduct of 5-trimethylsilylcyclopentadiene and dichloroketene

This paper described a first example of the application of the “abnormal” lactone of 3-oxabicyclo[3.3.0]oct-6-en-2-one topology in targeted prostaglandin synthesis.

Applications of Transition-Metal-Catalyzed Asymmetric Allylic Substitution in Total Synthesis of Natural Products: An Update

Metal-catalyzed asymmetric allylic substitution (AAS) reaction is one of the most synthetically useful reactions catalyzed by metal complexes for the formation of carbon-carbon and carbon-heteroatom bonds. It comprises the substitution of allylic substrates with a wide range of nucleophiles or S_N 2'-type allylic substitution, which results in the formation of the above-mentioned bonds with high levels of enantioselective induction. AAS reaction tolerates a broad range of functional groups, thus has been successfully applied in the asymmetric synthesis of a wide range of optically pure compounds. This reaction has been extensively used in the total synthesis of several complex molecules, especially natural products. In this review, we try to highlight the applications of metal (Pd, Ir, Mo, or Cu)-catalyzed AAS reaction in the total synthesis of the biologically active natural products, as a key step, updating the subject from 2003 till date.

Enantioselective Synthesis of 15-Deoxy-Δ12,14-Prostaglandin J2

An enantioselective synthesis of 15-deoxy-Δ^12,14-prostaglandin J₂ is reported. The synthesis begins with the preparation of enantiopure 3-oxodicyclopentadiene by a lipase-mediated kinetic resolution. A three-component coupling followed by a retro-Diels-Alder reaction provides the C8 stereochemistry of the prostaglandin skeleton with high enantioselectivity. Stereoretentive olefin metathesis followed by a Pinnick oxidation affords 15-deoxy-Δ^12,14-prostaglandin J₂ in high enantiopurity.

Short Total Synthesis of Δ12-Prostaglandin J2 and Related Prostaglandins. Design, Synthesis, and Biological Evaluation of Macrocyclic Δ12-Prostaglandin J2 Analogues

Comprised of a large collection of structurally diverse molecules, the prostaglandins exhibit a wide range of biological properties. Among them are Δ¹²-prostaglandin J₂ (Δ¹²-PGJ₂) and Δ¹²-prostaglandin J₃ (Δ¹²-PGJ₃), whose unusual structural motifs and potent cytotoxicities present unique opportunities for chemical and biological investigations. Herein, we report a short olefin-metathesis-based total synthesis of Δ¹²-PGJ₂ and its application to the construction of a series of designed analogues possessing monomeric, dimeric, trimeric, and tetrameric macrocyclic lactones consisting of units of this prostaglandin. Biological evaluation of these analogues led to interesting structure-activity relationships and trends and the discovery of a number of more potent antitumor agents than their parent naturally occurring molecules.

Concise Syntheses of Δ12-Prostaglandin J Natural Products via Stereoretentive Metathesis

Δ¹²-Prostaglandin J family is recently discovered and has potent anticancer activity. Concise syntheses of four Δ¹²-prostaglandin J natural products (7-8 steps in the longest linear sequences) are reported, enabled by convergent stereoretentive cross-metathesis. Exceptional control of alkene geometry was achieved through stereoretention.

Reoptimization of the Organocatalyzed Double Aldol Domino Process to a Key Enal Intermediate and Its Application to the Total Synthesis of Δ12 -Prostaglandin J3

Re-investigation of the l-proline catalyzed double aldol cascade dimerization of succinaldehyde for the synthesis of a key bicyclic enal intermediate, pertinent in the field of stereoselective prostaglandin synthesis, is reported. The yield of this process has been more than doubled, from 14 % to a 29 % isolated yield on a multi-gram scale (32 % NMR yield), through conducting a detailed study of the reaction solvent, temperature, and concentration, as well as a catalyst screen. The synthetic utility of this enal intermediate has been further demonstrated through the total synthesis of Δ12 -prostaglandin J3 , a compound with known anti-leukemic properties.

A stereoselective synthesis of the reported structure of polyporolide

A concise stereoselective synthesis of the reported structure of newly isolated acetogenin polyporolide is presented indicating a need for structure revision of the natural product.

Total synthesis of Δ¹²-prostaglandin J₃, a highly potent and selective antileukemic agent

A catalytic asymmetric total synthesis of the potent and selective antileukemic Δ(12)-prostaglandin J3 (Δ(12)-PGJ3) is described. The convergent synthesis proceeded through intermediates 2 and 3, formed enantioselectively from readily available starting materials and coupled through an aldol reaction followed by dehydration to afford stereoselectively the cyclopentenone alkylidene structural motif of the molecule.

Iridium-catalyzed enantioselective allylic substitution of unstabilized enolates derived from α,β-unsaturated ketones

We report Ir-catalyzed, enantioselective allylic substitution reactions of unstabilized silyl enolates derived from α,β-unsaturated ketones. Asymmetric allylic substitution of a variety of allylic carbonates with silyl enolates gave allylated products in 62-94% yield with 90-98% ee and >20:1 branched-to-linear selectivity. The synthetic utility of this method was illustrated by the short synthesis of an anticancer agent, TEI-9826.

Synthesis of the amino acid conjugates of epi-jasmonic acid

The TES ether of the C6-hydroxy derivative of naturally occurring epi-jasmonic acid (epi-JA) was designed as epimerization-free equivalent of epi-JA. The TES ether was synthesized from (1R,4S)-4-hydroxycyclopent-2-enyl acetate in 13 steps. The acid part of the ether was activated with ClCO2Bui and subjected to condensation with L-amino acid at room temperature for 48 h. The TES group in the condensation product was removed in HCO2H (0°C, 30 min) and the resulting hydroxyl group was oxidized with Jones reagent (acetone, 0°C, 30 min) to furnish the amino acid conjugate of epi-JA. The amino acids examined are L-isoleucine, L-leucine, L-alanine, L-valine, and D-allo-isoleucine, which afforded the conjugates in 48-68% yields with 89-96% diastereomeric purity over the trans isomers. Similarly, the possible three stereoisomers of epi-JA were condensed with L-isoleucine successfully, producing the corresponding stereoisomers in good yields.

Ligand-controlled selectivity in the desymmetrization of meso cyclopenten-1,4-diols via rhodium(I)-catalyzed addition of arylboronic acids

A highly enantioselective desymmetrization of meso cyclopent-2-ene-1,4-diethyl dicarbonates has been developed using a Rh-catalyzed asymmetric allylic substitution. Depending on the type of ligand used, each of two regioisomeric products can be obtained in good yield and excellent enantioselectivity. Under rhodium(I) catalysis, bisphosphine P-Phos ligands form trans-1,2-arylcyclopentenols as the major product, whereas Segphos ligands lead predominantly to trans-1,4-arylcyclopentenols.

Palladium-catalyzed decarboxylative rearrangements of allyl 2,2,2-trifluoroethyl malonates: direct access to homoallylic esters

Homoallylic esters are obtained in a single transformation from allyl 2,2,2-trifluoroethyl malonates by using a Pd(0) catalyst. Facile decarboxylation of allyl 2,2,2-trifluoroethyl malonates is attributed to a decrease in pK(a) compared to allyl methyl malonates. Subsequent reduction of the homoallylic 2,2,2-trifluoroethyl ester provides a (hydroxyethyl)cyclopentenyl derivative that represents a key intermediate in the synthesis of carbocyclic nucleosides. A select allyl 2,2,2-trifluoroethyl malonate undergoes a decarboxylative Claisen rearrangement to provide a regioisomeric homoallylic ester.

Structure based design of novel irreversible FAAH inhibitors

Fatty acid amide hydrolase (FAAH) has attracted significant attention due to its promise as an analgesic target. This has resulted in the discovery of numerous chemical classes as inhibitors of this potential therapeutic target. In this paper we disclose a new series of novel FAAH irreversible azetidine urea inhibitors. In general these compounds illustrate potent activity against the rat FAAH enzyme. Our SAR studies allowed us to optimize this series resulting in the identification of compounds 13 which were potent inhibitors of both human and rat enzyme. This series of compounds illustrated good hydrolase selectivity along with good PK properties.