Dihydroindole Derivatives Research Articles

A highly efficient method for the construction of cyclopropane-containing dihydroindole derivatives from indolemethylenecyclopropanes with DIAD and DEAD.

A highly efficient method for the construction of cyclopropane-containing dihydroindole derivatives from indolemethylenecyclopropanes with DIAD and DEAD has been disclosed. The transformation could occur under catalyst-free conditions at ambient temperature to afford dihyroindole derivatives in good yields. It has been proved that the strained moiety of methylenecyclopropane in the substrate of indolemethylenecyclopropane is critical and DFT calculations reveal that the reaction proceeds through a two-step pathway.

Selective C(sp3)–H Bond Insertion in Carbene/Alkyne Metathesis Reactions. Enantioselective Construction of Dihydroindoles

A general access to chiral dihydroindole derivatives in high yields is achieved by C–H functionalization in a highly site- and enantioselective cascade reaction of propargyl diazoacetates. Highly site-selective intramolecular C(sp3)–H bond insertions are realized by catalyst control. Sterically demanding dirhodium carboxylates, optimized with Rh2(S-BTPCP)4, favor C–H insertion into 1° C–H bonds with regioselectivities reaching >95:5 (1° > 2° benzylic) and >90% ee. With Rh2(S-TBPTTL)4, preferential 2° and 3° C–H bond insertion occurs due to the configuration of catalyst and electronic effects. The chiral dirhodium catalyst not only promotes carbene/alkyne metathesis (CAM) to generate the donor/donor carbene intermediate, but is also responsible for the observed asymmetric induction in the terminating C–H bond insertion reaction.

Evolution of a short route to strychnine by using the samarium-diiodide-induced cascade cyclization as a key step.

This comprehensive report accounts the development of a highly diastereoselective samarium diiodide-induced cascade reaction of substituted indolyl ketones. The complexity-generating transformation with SmI2 allows the diastereoselective generation of three stereogenic centers including one quaternary center in one step. The obtained tetra- or pentacyclic dihydroindole derivatives are structural motifs of many monoterpene indole alkaloids, and their subsequent transformations gave way to one of the shortest approaches towards strychnine (14 % overall yield in ten steps, or 10 % overall yield in eight steps). During the course of this report we discuss the influence of substituents on the cyclization step, plausible mechanistic scenarios for the SmI2 -induced cascade reaction, diastereoselective reductive amination, and regioselective dehydratization protocols towards the pentacyclic core structure of strychnos alkaloids.

ChemInform Abstract: New Samarium Diiodide Induced Cyclizations

AbstractReview: 44 refs.

New samarium diiodide-induced cyclizations

Samarium diiodide (SmI2) smoothly promotes the cyclizations of suitably substituted carbonyl compounds with styrene subunits leading to benzannulated cyclooctenes. The intramolecular samarium ketyl addition to arene or hetarene moieties enables a new, efficient, and highly stereoselective entry to dearomatized products such as hexahydronaphthalenes, steroid-like tetra- or pentacyclic compounds, or dihydroindole derivatives. The usefulness of the developed SmI2-induced cyclization method was demonstrated by the shortest formal total synthesis of the alkaloid strychnine.

Synthesis of Dihydroindoles and Tetrahydroquinolines by the Intramolecular Diels-Alder Reaction of N-Alkenylated 2-Acylamino-3-furancarbonitriles

An approach to dihydroindoles and tetrahydroquinolines from N-alkenylated 2-acylamino-3-furancarbonitriles via a [4 + 2] cycloaddition reaction is described. Thermal treatment of N-alkenylated 2-acylamino-3-furancarbonitriles 5a-d, 6a-d, 9a-d, and 10a-d, which were prepared from 2-acylamino-3-furancarbonitriles 3a-d and/or 4a-d and 4-bromo-1-butene and/or 5-bromo-1-pentene, caused an intramolecular Diels-Alder reaction to give the corresponding dihydroindole and tetrahydroquinoline derivatives 7a-d, 8a-d, 11a-d, and 12a-d. This method has the advantage of easier work-up procedure.

ChemInform Abstract: Tricyclic Indole and Dihydroindole Derivatives as New Inhibitors of Soluble Guanylate Cyclase.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.

Tricyclic indole and dihydroindole derivatives as new inhibitors of soluble guanylate cyclase

The synthesis of new tricyclic fused indole and dihydroindole derivatives and preliminary results from their in vitro inhibitory activity against soluble guanylate cyclase (sGC) are presented.

Reductive Heck cyclization versus δ-carbon elimination/decarboxylation: synthesis of dihydroindole and indoles from Baylis–Hillman adducts

Modified Baylis–Hillman adducts having 2-bromoaniline moiety at the primary position underwent Pd-mediated reductive Heck type cyclization to produce dihydroindole derivatives. The same starting materials can also be used for the synthesis of indole derivatives under slightly different conditions via the concomitant δ-carbon elimination and decarboxylation process.

Highly Substituted Dihydroindole Derivatives by Intermolecular Couplings of Samarium Ketyls and Indoles.

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Highly Substituted Dihydroindole Derivatives by Intermolecular Couplings of Samarium Ketyls and Indoles

Samarium diiodide promoted intermolecular reductive couplings of ketones and aldehydes to 3-methoxycarbonyl-substituted indole derivatives afforded dihydroindoles in good yields and with excellent diastereoselectivities. Trapping of the intermediate samarium enolate with allyl iodide furnished tricyclic lactones with good efficacy, thus demonstrating the potential of this method for the construction of structurally complex indole derivatives by a three-component protocol.

Synthesis of Na-Methoxyindole and Na-Methoxyoxindole Alkaloids Having Yohimbine Skeleton

Indoloquinolizidine (1) and yohimbine (7) were converted to the corresponding N a -methoxyindoles and N a -methoxyoxindoles by the oxidation of the dihydroindole derivatives with H 2 O 2 and sodium tungstate

ChemInform Abstract: Electron Impact Induced Loss of C‐5/C‐8 Substituents of 1,2,3,4‐Tetrahydroisoquinolines. Part 6. Synthesis and Mass Spectrometric Fragmentation of Dihydroindole Derivatives.

AbstractStarting with indole‐4‐carboxaldehyde (I), the dihydroindoles (VI) are synthesized as outlined in the reaction scheme.

Electron Impact Induced Loss of C‐5/C‐8 Substituents of 1,2,3,4‐Tetrahydroisoquinolines, VI1): Synthesis and Mass Spectrometric Fragmentation of Dihydroindole Derivatives

AbstractThe syntheses of the C‐4 substituted dihydroindoles 25, 31 (scheme 7), and 36 (scheme 8) are described. ‐ The CID MIKE spectrum in the 2. field free region (2. FFR) of m/z 146 from 25 is very similar to but not identical with that of m/z 146 from the C‐5 substituted tetrahydroisoquinolines 3, 6, 7, and 8 (scheme 2), so supporting our hypothesis of a rearrangement in M+ of tetrahydroisoquinolines1) prior to fragmentation, but not proving it. As the CID MIKE spectra of the tetrahydroisoquinolines 3, 6, 7, and 8 are not identical among each other we assume that a 1.3‐H‐shift takes places in their M+ in competition to the rearrangement mentioned above.

Transfer of functionalized carbon fragments via substituted 5, 10-methylentetetrahydrofolate models. : Approach to dihydroindole and indole alkaloids.

4-(2-N(1)-tosyl-N(3)-methyl-4-,4-dimethylimidazolidyl)-3-ketobutanoate reacts with tryptamine, in the presence of acetic acid, to give primary “carbon transfer” products, which can be conveniently converted to synthetically useful indole and dihydroindole derivatives.

Alcaloïdes Indoliques. XIX. Un Nouvel Exemple D'empêchement a la Libre Rotation Dans des Dérivés Dihydroindoliques N‐Formylés

AbstractThe proton magnetic resonance spectra of some N‐formyl dihydroindole derivatives have been investigated. The data are best rationalized on the basis of a hindered rotation about the N–CHO bond.The attribution of the signals to each conformation is obtained from the chemical shifts in the low field region and from the pattern of the aromatic protons.