Samarium Diiodide Research Articles

Diastereoselective synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones via SmI2-mediated reductive coupling of 2-alkylacrylates of N,N-diisopropyl-2-hydroxybenzamide with aldehydes

Samarium(II) diiodide has been used to mediate reductive coupling reactions of aldehydes with a variety of substituted acrylates, in both achiral and chiral forms, for accessing substituted dihydrofuran-2(3H)-ones (γ-butyrolactones). Two major issues, concerning with self-dimerization of α-non-branched aliphatic aldehydes and low diastereoselectivity of the products, render limited application of the reductive coupling protocol in total synthesis of natural products. We report here on a novel type of substituted acrylates derived from the 2-amido arenols (HO-Aram) such as N,N-diisopropyl-2-hydroxybenzamide. The acrylates of HO-Aram enable: (a) preferential conjugate reduction of the acrylates than carbonyl reduction of aliphatic aldehydes, leading to diminished aldehyde self-dimerization; and (b) organization of an eight-membered ring among the amide carbonyl oxygen atom and samarium(III) to form a 7/8-bicyclic transition state, resulting in highly diastereoselective protonation of the samarium(III) enolate intermediate. Examples of synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones from 2-alkylacrylates of HO-Aram and aliphatic aldehydes are provided.

ChemInform Abstract: Strychnine as Target, Samarium Diiodide as Tool: A Personal Story

AbstractReview: [36 refs.

ChemInform Abstract: Construction of Pyrrolophenanthridinone Scaffolds Mediated by Samarium(II) Diiodide and Access to Natural Product Synthesis.

AbstractA facile methodology for the construction of pyrrolophenanthridinone derivatives via a SmI2‐mediated reductive cyclization is developed and applied to the concise synthesis of the natural product anhydrolycorinone (IV).

Reductive opening of carbohydrate phenylsulfonylethylidene (PSE) acetals

The phenylsulfonylethylidene (PSE) acetal is a relatively new protecting group in carbohydrate chemistry. However, carbohydrate-derived phenylsulfonylethylidene (PSE) acetals show a different behavior in reductive desulfonylation than simple symmetrical acetals. Here we have investigated various SET-type reaction conditions in order to open PSE acetals regioselectively and to produce chiral ω-hydroxyethenyl ethers. Whereas sodium amalgam leads to a mixture of regioisomeric vinyl ethers besides the ethylidene acetal, samarium iodide is suited for regioselective ring opening. This is shown with seven different carbohydrate PSE acetals, both of the 1,3-dioxane and the 1,3-dioxolane type.

ChemInform Abstract: Synthesis of 3‐Ethenylindoles via Intramolecular Cyclization of Aryl Radical with Allene Generated by Samarium(II) Diiodide.

ChemInform Abstract: Synthesis of 3‐Ethenylindoles via Intramolecular Cyclization of Aryl Radical with Allene Generated by Samarium(II) Diiodide.

Strychnine as Target, Samarium Diiodide as Tool: A Personal Story.

Strychnine stands out from the group of classical natural products as one of the first complex compounds to be isolated in pure form and an extreme challenge to be structurally characterized. It has played a central role in natural product total syntheses and the surge in the development of innovative synthetic methods for many decades. Recently, we have accomplished one of the shortest formal total syntheses of strychnine (in ten steps and 14% overall yield or even shorter in eight steps and 10% overall yield). The evolution of a productive synthetic strategy, as well as the synthetic challenges tackled, are described here in detail, including examples of related transformations. The successful synthetic strategy was inspired by the premise that the core structure could be derived from simple aromatic indole precursors by a reductive SmI2 -induced ketyl-aryl coupling. Other key reactions included a diastereoselective reduction and a regioselective elimination protocol. Altogether one of the shortest syntheses of iso-strychnine and hence of strychnine was established.

ChemInform Abstract: Samarium Diiodide Mediated Coupling of 2‐Pyridylsulfonyl Furanosides with Aldehydes and Ketones: A General Synthesis of C‐Furanosides.

ChemInformVolume 46, Issue 33 Natural Products ChemInform Abstract: Samarium Diiodide Mediated Coupling of 2-Pyridylsulfonyl Furanosides with Aldehydes and Ketones: A General Synthesis of C-Furanosides. Jin Wang, Jin Wang Inst. Pharmacol. Biol. Struct., CNRS, F-31077 Toulouse, Fr.Search for more papers by this authorFabien Gasc, Fabien Gasc Inst. Pharmacol. Biol. Struct., CNRS, F-31077 Toulouse, Fr.Search for more papers by this authorJacques Prandi, Jacques Prandi Inst. Pharmacol. Biol. Struct., CNRS, F-31077 Toulouse, Fr.Search for more papers by this author Jin Wang, Jin Wang Inst. Pharmacol. Biol. Struct., CNRS, F-31077 Toulouse, Fr.Search for more papers by this authorFabien Gasc, Fabien Gasc Inst. Pharmacol. Biol. Struct., CNRS, F-31077 Toulouse, Fr.Search for more papers by this authorJacques Prandi, Jacques Prandi Inst. Pharmacol. Biol. Struct., CNRS, F-31077 Toulouse, Fr.Search for more papers by this author First published: 28 July 2015 https://doi.org/10.1002/chin.201533240Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume46, Issue33August, 2015 RelatedInformation

Construction of pyrrolophenanthridinone scaffolds mediated by samarium(II) diiodide and access to natural product synthesis

Pyrrolophenanthridinone derivatives including the natural products were readily synthesized by samarium(II)-mediated reductive cyclization of aryl radical onto a benzene ring under mild reaction conditions. This methodology was applied to the concise synthesis of anhydrolycorinone, a natural pyrrolophenanthridinone and a precursor of hippadine and anhydrolycorine.

ChemInform Abstract: Synthesis of Polycyclic Tertiary Carbinamines by Samarium Diiodide Mediated Cyclizations of Indolyl Sulfinyl Imines.

Samarium diiodide mediated cyclizations of N-acylated indole derivatives bearing sulfinyl imine moieties afforded polycyclic tertiary carbinamines with moderate to excellent diastereoselectivities. Lithium bromide and water turned out to be the best additives to achieve these transformations in good yields. Using enantiopure sulfinyl imines the outcome strongly depends on the reactivity of the indole moiety. Whereas with unactivated indole derivatives desulfinylation and formation of racemic products was observed, indoles bearing electron-withdrawing substituents at C-3 afforded the polycyclic products with intact N-sulfinyl groups and with excellent diastereoselectivity, finally allowing the preparation of enantiopure tertiary carbinamines. The mechanisms of these processes are discussed.

Pinacol couplings of a series of aldehydes and ketones with SmI2/Sm/Me3SiCl in DME

The pinacol coupling is one of the most significant methods to synthesize vic-diols. The combination of samarium diiodide (SmI2) and samarium metal successfully induces the selective pinacol couplings of not only aromatic aldehydes and ketones but also aliphatic ones in the presence of trimethylchlorosilane (Me3SiCl) in 1,2-dimethoxyethane (DME). DME is the most suitable solvent for the reduction system using SmI2 and Me3SiCl. Me3SiCl, a widely available additive, prevents the decomposition of the formed vic-diols, i.e., meso-isomers, and controls their stereochemistry. In particular, the pinacol couplings of sterically hindered aliphatic aldehydes and ketones proceed with excellent diastereoselectivities to afford dl-isomers in good yields.

ChemInform Abstract: Synthesis of Indolines via a SmI2 Promoted Domino Nitro Reduction‐Intramolecular aza‐Michael Reaction.

A simple and straightforward synthesis of substituted indolines based on a domino nitro reduction intramolecular aza-Michael reaction is described. The reaction employs Samarium diiodide under mild conditions for the addition of dibromoacetic acid to substituted 2-(2-nitrophenyl) acetaldehyde derivatives and their subsequent cyclization upon nitro group reduction to provide corresponding indoline heterocycles in good yields. This “one pot” strategy also permitted the expeditious synthesis of a 1,2,3,4-tetrahydroquinoline, whereas the seven-membered 2,3,4,5-tetrahydrobenzoazepines compounds were not formed under these reaction conditions.

Design and Synthesis of Labystegines, Hybrid Iminosugars from LAB and Calystegine, as Inhibitors of Intestinal α-Glucosidases: Binding Conformation and Interaction for ntSI.

This paper identifies the required configuration and orientation of α-glucosidase inhibitors, miglitol, α-1-C-butyl-DNJ, and α-1-C-butyl-LAB for binding to ntSI (isomaltase). Molecular dynamics (MD) calculations suggested that the flexibility around the keyhole of ntSI is lower than that of ctSI (sucrase). Furthermore, a molecular-docking study revealed that a specific binding orientation with a CH-π interaction (Trp370 and Phe648) is a requirement for achieving a strong affinity with ntSI. On the basis of these results, a new class of nortropane-type iminosugars, labystegines, hybrid iminosugars of LAB and calystegine, have been designed and synthesized efficiently from sugar-derived cyclic nitrones with intramolecular 1,3-dipolar cycloaddition or samarium iodide catalyzed reductive coupling reaction as the key step. Biological evaluation showed that our newly designed 3(S)-hydroxy labystegine (6a) inherited the selectivity against intestinal α-glucosidases from LAB, and its inhibition potency was 10 times better than that of miglitol. Labystegine, therefore, represents a promising new class of nortropane-type iminosugar for improving postprandial hyperglycemia.

Samarium Diiodide Mediated Coupling of 2‐Pyridylsulfonyl Furanosides with Aldehydes and Ketones: A General Synthesis of C‐Furanosides

AbstractDiiodosamarium‐mediated coupling of anomeric 2‐pyridyl sulfones derived from furanosides with carbonyl compounds, aldehydes, and ketones gave α‐hydroxylated 2,5‐trans‐dialkylated tetrahydrofurans with good yields and useful stereoselectivities. The main control element of the reaction is the substituent on the 4‐position or the starting furanosyl sulfone. C‐Furanosides of D‐arabinose and of D‐ribose were obtained from sulfones prepared from the corresponding furanosides. Finally, a di‐C‐arabinofuranoside, a C‐disaccharide analogue of a major motif of the arabinogalactan from the mycobacterial cell wall, was prepared.

ChemInform Abstract: Indole Synthesis from N‐Allenyl‐2‐iodoanilines under Mild Conditions Mediated by Samarium(II) Diiodide.

A novel method for indole skeleton synthesis under mild conditions mediated by samarium(II) diiodide has been developed. The reaction of N-allenyl-2-iodoaniline derivatives with SmI2 in the presence of HMPA and i-PrOH at 0 °C afforded indole derivatives in high yields.

Synthesis of polycyclic tertiary carbinamines by samarium diiodide mediated cyclizations of indolyl sulfinyl imines.

Samarium diiodide mediated cyclizations of N-acylated indole derivatives bearing sulfinyl imine moieties afforded polycyclic tertiary carbinamines with moderate to excellent diastereoselectivities. Lithium bromide and water turned out to be the best additives to achieve these transformations in good yields. Using enantiopure sulfinyl imines the outcome strongly depends on the reactivity of the indole moiety. Whereas with unactivated indole derivatives desulfinylation and formation of racemic products was observed, indoles bearing electron-withdrawing substituents at C-3 afforded the polycyclic products with intact N-sulfinyl groups and with excellent diastereoselectivity, finally allowing the preparation of enantiopure tertiary carbinamines. The mechanisms of these processes are discussed.

Synthesis of 3-Ethenylindoles via Intramolecular Cyclization of Aryl Radical with Allene Generated by Samarium(II) Diiodide

Synthesis of 3-Ethenylindoles via Intramolecular Cyclization of Aryl Radical with Allene Generated by Samarium(II) Diiodide

ChemInform Abstract: Stereoselective Access to Trisubstituted Cyclopentanols from Chiral Unsaturated Oxo Esters by Ketyl Radical Cyclization.

Substituted cyclopentanols with three contiguous stereocenters were prepared with impressive diastereocontrol through a samarium diiodide induced 5-exo-trig radical process. The chiral unsaturated oxo ester precursors were prepared with ee values up to 90 % from propionaldehyde through a two-step organocatalyzed aldolization and Wittig–Horner olefination reaction sequence.

ChemInform Abstract: Aza‐Reformatsky Reaction Promoted by Catalytic Samarium Diiodide: Synthesis of β‐Amino Esters or Amides.

The synthesis of β-amino esters or amides has been achieved from moderate to high yields from the reaction of imines and α-halo esters or amides promoted by catalytic amounts of ­samarium diiodide in the presence of magnesium turnings as co-­reductant. A mechanism is proposed to explain this catalytic samarium(II)-promoted aza-Reformatsky reaction.

Preparation of Multivalent Carbohydrate Mimetics Based on Enantiopure 1,2‐Oxazines by Sonogashira Coupling and Subsequent Reductive Ring‐Opening

AbstractA modular approach to aryl C‐glycosides and their multivalent analogues is presented. Sonogashira coupling reactions connected the key compounds, enantiopure bicyclic 1,2‐oxazine derivatives bearing p‐bromophenyl substituents, with alkynes. Subsequent hydrogenolyses or a combination of hydrogenolysis and samarium diiodide mediated reductions converted the coupling products into new unnatural amino carbohydrate mimetics with a D‐talose configuration. By Glaser coupling reactions we obtained products with a 1,3‐diyne linker and divalent compounds derived therefrom. Through Sonogashira reactions of compound 8 with several iodobenzene derivatives, di‐, tri‐, and tetravalent compounds were prepared in high yields. The subsequent reductive processes converted the 1,2‐oxazine moieties into the corresponding aminopyrans. Severe purification problems were solved in most cases by following the appropriate strategies as an apt sequence of steps or by acetylation of the intermediates.

Catalytic reduction of CN-, CO, and CO2 by nitrogenase cofactors in lanthanide-driven reactions.

Nitrogenase cofactors can be extracted into an organic solvent to catalyze the reduction of cyanide (CN(-)), carbon monoxide (CO), and carbon dioxide (CO2) without using adenosine triphosphate (ATP), when samarium(II) iodide (SmI2) and 2,6-lutidinium triflate (Lut-H) are employed as a reductant and a proton source, respectively. Driven by SmI2, the cofactors catalytically reduce CN(-) or CO to C1-C4 hydrocarbons, and CO2 to CO and C1-C3 hydrocarbons. The C-C coupling from CO2 indicates a unique Fischer-Tropsch-like reaction with an atypical carbonaceous substrate, whereas the catalytic turnover of CN(-), CO, and CO2 by isolated cofactors suggests the possibility to develop nitrogenase-based electrocatalysts for the production of hydrocarbons from these carbon-containing compounds.