Stereoselective Intramolecular Diels-Alder Reaction Research Articles

Divergent syntheses of complex Veratrum alkaloids

The Veratrum alkaloids are a class of highly intricate natural products renowned for their complex structural and stereochemical characteristics, which underlie a diverse array of pharmacological activities ranging from anti-hypertensive properties to antimicrobial effects. These properties have generated substantial interest among both synthetic chemists and biologists. While numerous advancements have been made in the synthesis of jervanine and veratramine subtypes over the past 50 years, the total synthesis of highly oxidized cevanine subtypes has remained relatively scarce. Building on the efficiency of our previously developed strategy for constructing the hexacyclic carbon skeleton of the Veratrum alkaloid family via a stereoselective intramolecular Diels-Alder reaction and radical cyclization, here we show the development of a unified synthetic approach to access highly oxidized Veratrum alkaloids. This includes the total synthesis of (–)-zygadenine, (–)-germine, (–)-protoverine and the alkamine of veramadine A, by capitalizing on a meticulously designed sequence of redox manipulations and a late-stage neighboring-group participation strategy.

Enantioselective Total Synthesis of (-)-Zygadenine.

The Veratrum alkaloids are highly complex steroidal alkaloids characterized by their intricate structural and stereochemical features and exhibit a diverse range of pharmacological activities. A new synthetic pathway has been developed to access this family of natural products, which enabled the first total synthesis of (-)-zygadenine. This synthetic route entails the construction of a hexacyclic carbon skeleton through a stereoselective intramolecular Diels-Alder reaction, followed by a radical cyclization. Subsequently, a meticulously designed sequence of redox manipulations was optimized to achieve the de novo synthesis of this highly oxidized Veratrum alkaloid.

Asymmetric Total Synthesis of (+)-Coprophilin

In this paper, we report the first total synthesis of (+)-coprophilin, an anticoccidial agent, by constructing the chiral linear precursor via a Mukaiyama–Evans aldol reaction and a stereoselective intramolecular Diels–Alder reaction. The proposed method can be used to provide large amounts of (+)-coprophilin, which exhibits a 3,4,5,6,7-pentasubstituted Δ1,2-octalin core structure.

Enantio- and Stereoselective Construction of Atisane Scaffold via Organocatalytic Intramolecular Michael Reaction and Diels-Alder Reaction.

An enantio- and stereoselective construction of the atisane scaffold via organocatalytic intramolecular Michael reaction and Diels-Alder reaction is described. The organocatalytic intramolecular Michael reaction has been found to stereoselectively generate a trans-stereodiad comprising an all-carbon quaternary and a tertiary stereogenic centers. Use of the chiral secondary amine bearing thiourea with benzoic acid as additive is the key to obtaining the desired product with excellent ee in synthetically acceptable yield. The prepared chiral building block has been successfully converted to the compound including the atisane scaffold via the highly stereoselective intramolecular Diels-Alder reaction.

A highly stereoselective intramolecular Diels–Alder reaction for construction of the AB ring moiety of bruceantin

A highly stereoselective intramolecular Diels–Alder (IMDA) reaction for the construction of the AB ring moiety of bruceantin is described. The product of the IMDA reaction comprises a trans-AB ring junction and stereotetrad including an all carbon quaternary stereogenic center, wherein three stereogenic centers correspond to those of bruceantin. Functional groups embedded in the product are suitable for a variety of transformations. Hence, this IMDA product could be a useful intermediate for the enantioselective total synthesis of not only bruceantin, but also other bioactive compounds.

Total synthesis of (-)-depyranoversicolamide B.

Starting from easily prepared (R)-C3-isoprenylated pyrroloindoline, the C3-isoprenylated indolyl diketopiperazine is prepared by an efficient reductive opening of the pyrrolo ring, and undergoes biomimetic Diels-Alder reaction to generate an anti-adduct as a sole stereoisomer. Oxidation of the indoline moiety to oxindole completes the synthesis of (-)-depyranoversicolamide B.

Total Synthesis of AMF-26, an Antitumor Agent for Inhibition of the Golgi System, Targeting ADP-Ribosylation Factor 1

An effective method for the total synthesis of 1 (AMF-26), a potentially promising new anticancer drug that disrupts the Golgi system by inhibiting the ADP-ribosylation factor 1 (Arf1) activation, has been developed for the first time. The construction of the chiral linear precursor (a key to the synthesis) was achieved by the asymmetric aldol reaction followed by the computer-assisted predictive stereoselective intramolecular Diels-Alder reaction. The global antitumor activity of the totally synthetic 1 against a variety of human cancer cells was assessed using a panel of 39 human cancer cell lines (JFCR39), and it was shown that the synthetic 1 strongly inhibited the growth of several cancer cell lines at concentrations of less than 0.04 μM. Biological assays of novel derivatives, 26 and 31, which have different side-chains at the C-4 positions in the Δ¹,²-octalin backbone, disclosed the importance of the suitable structure of the side-chain containing conjugated multidouble bonds.

Toward the Total Synthesis of (±)-Andrastin C

An efficient approach to generate a fully functionalized cyclopenta[a]phenanthrene 34, the basic carbon framework of andrastin C (1c), is described. The present synthetic route features a stereoselective intramolecular Diels-Alder reaction of triene 12 and an intramolecular carbonyl ene reaction of 3-phenanthrenyl-2-(methoxymethoxy)propanal 31.

Construction of A/E/F ring systems of C19-diterpenoid alkaloids with both C-1 and C-6 oxygen functions

An tricyclic AEF fragment of C19-diterpenoid alkaloid bearing an angular methyl group and the oxygen function groups at C-1 and C-6 was successfully synthesized. The synthesis features a stereoselective intramolecular Diels–Alder reaction and a highly efficient intramolecular Mannich reaction as well as efficient functional groups transformations.

Total Synthesis of (+)-Yohimbine via an Enantioselective Organocatalytic Pictet–Spengler Reaction

The binolphosphoric acid-catalyzed Pictet-Spengler reaction of an N-(5-oxy-2,4-pentadienyl)tryptamine derivative with methyl 5-oxo-2-(phenylseleno)pentanoate leads to the tetrahydro-β-carboline in a 92:8 enantiomeric ratio. This product is easily converted into the substrate for a stereoselective intramolecular Diels-Alder reaction of the type earlier reported by Jacobsen. These two key steps constitute the basis for a nine-step total synthesis of (+)-yohimbine from tryptamine. A similar asymmetric Pictet-Spengler reaction was applied to the synthesis of an intermediate in the recent total synthesis of corynantheidine by Sato.

ChemInform Abstract: Highly Stereoselective Intramolecular Diels—Alder Reaction of Decatrienoates Activated by t‐Butoxycarbonyl, Chloro, and Sulfonyl Groups at the Terminal Position.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Highly Stereoselective Intramolecular Diels–Alder Reaction of Decatrienoates Activated by t-Butoxycarbonyl, Chloro, and Sulfonyl Groups at the Terminal Position

Abstract Highly stereoselective intramolecular Diels–Alder (IMDA) reaction of decatrienoates has been achieved by using a more sterically hindered ester group, i.e., t-butoxycarbonyl, or electron-withdrawing hetero substituents, i.e., chloro and phenylsulfonyl, as terminal activating groups. A remarkable olefin isomerization of the Diels–Alder cycloadduct bearing a phenylsulfonyl group occurred upon heating it for a few hours and it was found that the isomerization can be catalyzed by Brønsted acid.

Utility of a chiral 1,3-dioxane template in stereoselective intramolecular Diels–Alder reactions

The ethylidene acetal of d-erythrose was used as a template for stereoselective IMDA reactions: high endo selectivity and yields in favor of the cis product were observed with 1,3,9-trienes, resulting from a boat transition state. For natural product synthesis, the reaction was successfully applied to a diene with terminal Z-olefin.

Total Synthesis of the Fusarium Toxin Equisetin.

A short stereoselective synthesis of the Fusarium toxin equisetin, a potent inhibitor of HIV-1 integrase enzyme is described, using as the key step a stereoselective intramolecular Diels–Alder reaction of a fully conjugated E,E,E-triene with a trisubstituted γ,δ-unsaturated β-ketothioester.

Total synthesis of the Fusarium toxin equisetin

A short stereoselective synthesis of the Fusarium toxin equisetin, a potent inhibitor of HIV-1 integrase enzyme is described, using as the key step a stereoselective intramolecular Diels-Alder reaction of a fully conjugated E,E,E-triene with a trisubstituted gamma,delta-unsaturated beta-ketothioester.

Synthesis of Densely Functionalized Pyrrolidinone Templates by an Intramolecular oxo‐Diels—Alder Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of densely functionalized pyrrolidinone templates by an intramolecular oxo-Diels–Alder reaction

Preparation of densely functionalized pyrrolidinone templates, is a challenge for synthetic chemists. These templates are important building blocks for novel conformationally constrained natural products or for library generation of highly functionalized bi or polycyclic compounds. We discovered that trienes 6a– j undergo facile stereoselective intramolecular Diels–Alder reactions to generate densely functionalized cis fused pyrrolidinone templates 1a– j . These reactions allow for directed remote hydroxylation with complete control of stereochemistry.

Total synthesis of (−)-mniopetal F, a novel inhibitor of RNA-directed DNA-polymerases

We have achieved a total synthesis of (−)-mniopetal F, a drimane-type sesquiterpenoid which inhibits the reverse transcriptase activity of the human immunodeficiency virus (HIV)-1. The key step in our enantiospecific synthesis is a stereoselective intramolecular Diels–Alder reaction, in which the π-facial selectivity is controlled by the stereoelectronic effect of a trialkylsilyloxy substituent existing adjacent to the dienophile part.

Total synthesis of (−)-mniopetal E, a novel biologically intriguing drimane sesquiterpenoid

Total synthesis of (−)-mniopetal E, the common skeleton of the biologically intriguing mniopetals A-D, was accomplished for the first time. The key step of the total synthesis was stereoselective intramolecular Diels-Alder reaction for construction of the octahydronaphthalene core structure. Our total synthesis as natural enantiomeric form established the unsettled absolute stereochemistry of the antibiotic.

The Enantioselective Total Synthesis of (−)-Myltaylenol

The unusual sesquiterpenoid alcohol (−)-myltaylenol, which bears three consecutive quartenary carbon atoms, is synthesized in an overall yield of 6.5 % (below). The key step of the synthesis is a stereoselective intramolecular Diels–Alder reaction of a vinyl sulfonic ester followed by a novel oxidative ring cleavage employing molecular oxygen and giving rise to a hydroxyketone directly.