Tandem Radical Reactions Research Articles

Visible-Light-Induced Three-Component Radical Coupling of Selenocarbamates, Enones, and Allylstannanes with Diphenyl (2,4,6-trimethylbenzoyl)phosphine Oxide

AbstractA blue LED-induced three-component coupling of a carbamoyl radical, cyclic enone, and allylstannane was developed. The use of blue LEDs and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as a radical initiator permitted the three-component radical coupling to proceed with a high chemoselectivity. An elucidation of the mechanism revealed a pathway for the formation of a tributyltin radical from TPO and allylstannane. This tandem radical reaction is expected to be applicable in natural-product synthesis.

Photochemical Synthesis of S,N,O-Containing Polyheterocycles via an α-C(sp3)-H Functionalization/Radical Cyclization Cascade.

A highly effective approach based on an organophotocatalytic α-C(sp3)-H functionalization/radical cyclization cascade has been developed. This method enables the synthesis of various tricyclic heterocycles containing S, O, and N atoms with excellent site selectivity and diastereoselectivity. Mechanistic investigations have confirmed that the reaction involves photoredox-triggered C(sp3)-H cleavage followed by a radical cyclization and aromatization process. These findings are expected to pave the way for developing cost-effective tandem radical reactions and synthesizing heterocyclic drugs.

Electrophotocatalytic Si–H Activation Governed by Polarity-Matching Effects

Electrophotocatalytic Si–H Activation Governed by Polarity-Matching Effects

Formal Synthesis of (-)-Haliclonin A: Stereoselective Construction of an Azabicyclo[3.3.1]nonane Ring System by a Tandem Radical Reaction.

A formal synthesis of (-)-haliclonin A, isolated from the marine sponge Haliclona sp. in Korea, is described. The key feature of the synthesis includes the highly stereoselective tandem radical reaction to construct the azabicyclo[3.3.1]nonane core and the enantioselective formation of an all-carbon quaternary center via the Pd-mediated deracemization.

Total Synthesis of (±)-Prostratin

Summary Prostratin, a highly complex diterpene natural product, is a pre-clinical candidate in developing a cure for HIV-1 infection and also a potent and selective inhibitor of several tumors. Despite nearly 40 years of progress, prostratin and related natural products still present formidable challenges for synthetic chemists. Here, we report a total synthesis of (±)-prostratin that proceeds in 23 steps from cyclopentadiene. The synthetic strategy includes rapid assembly of the tricyclic core and highly controlled establishment of the densely functionalized C ring, featuring an array of stereoselective transformations including alkoxide-guided 1,4-additions and cyclopropane formation. This work should enable further explorations of chemical and biological spaces based on prostratin and related natural products.

Copper‐Promoted Tandem Radical Reaction of 2‐Oxindoles with Formamides: Facile Synthesis of Unsymmetrical Urea Derivatives

AbstractA convenient copper‐promoted tandem radical reaction of 2‐oxindoles with formamides producing unsymmetrical urea derivatives is described. This radical‐mediated reaction enables the formation of one C=O and one C−N bond through a domino C−O coupling, ring cleavage and C−N coupling process, which features a broad substrate scope and excellent selectivity. In addition, tBuOOH not only acts as the oxidant, but also as the oxygen source. The proposed reaction mechanism is supported by control experiments.

ChemInform Abstract: Radical Aryl Migration Reactions and Synthetic Applications

AbstractReview: [114 refs.

ChemInform Abstract: Titanocene(III) Chloride Mediated Stereoselective Synthesis of Trisubstituted Tetrahydrofurans and a Spirolactone by Tandem Radical Reactions.

ChemInformVolume 46, Issue 6 Heterocyclic Compounds ChemInform Abstract: Titanocene(III) Chloride Mediated Stereoselective Synthesis of Trisubstituted Tetrahydrofurans and a Spirolactone by Tandem Radical Reactions. Shirshendu Mukherjee, Shirshendu Mukherjee Dep. Org. Chem., Indian Assoc. Cultiv. Sci., Kolkata 700 032, IndiaSearch for more papers by this authorRajdip Roy, Rajdip Roy Dep. Org. Chem., Indian Assoc. Cultiv. Sci., Kolkata 700 032, IndiaSearch for more papers by this authorSubhas Chandra Roy, Subhas Chandra Roy Dep. Org. Chem., Indian Assoc. Cultiv. Sci., Kolkata 700 032, IndiaSearch for more papers by this author Shirshendu Mukherjee, Shirshendu Mukherjee Dep. Org. Chem., Indian Assoc. Cultiv. Sci., Kolkata 700 032, IndiaSearch for more papers by this authorRajdip Roy, Rajdip Roy Dep. Org. Chem., Indian Assoc. Cultiv. Sci., Kolkata 700 032, IndiaSearch for more papers by this authorSubhas Chandra Roy, Subhas Chandra Roy Dep. Org. Chem., Indian Assoc. Cultiv. Sci., Kolkata 700 032, IndiaSearch for more papers by this author First published: 23 January 2015 https://doi.org/10.1002/chin.201506123Read 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, Issue6February, 2015 RelatedInformation

Radical-polar crossover reactions: oxidative coupling of 1,3-dioxolanes with electron-deficient alkenes and vinylarenes based on a radical addition and Kornblum-DeLaMare rearrangement.

A new radical-polar crossover reaction has been developed involving the combination of a tandem radical reaction and Kornblum-DeLaMare rearrangement in a one-pot process. This simple methodology allows for the construction of polyfunctionalized carbonyl compounds via the oxidative coupling of 1,3-dioxolanes with electron-deficient alkenes and vinylarenes in the presence of Co(salen) and TBHP under mild conditions. This reaction also exhibited high functional group tolerance, wide substrate scope, and operational simplicity.

Titanocene(III) Chloride Mediated Stereoselective Synthesis of Trisubstituted Tetrahydrofurans and a Spirolactone by Tandem Radical Reactions

AbstractThe titanocene(III) chloride (Cp2TiCl) mediated stereoselective synthesis of highly substituted tetrahydrofurans has been achieved by a reaction that proceeds through a tandem radical cyclization reaction between a Baylis–Hillman adduct and an activated bromo/iodo compound. The reaction of an epoxide with the Baylis–Hillman adduct furnished a spirolactone through a radical cyclization followed by an in situ lactonization. Cp2TiCl was prepared in situ from commercially available Cp2TiCl2and zinc dust in tetrahydrofuran.

ChemInform Abstract: Synthesis of (2‐Alkylthiothiazolin‐5‐yl)methyl Dodecanoates via Tandem Radical Reaction.

AbstractA series of title compounds (III) is synthesized from N‐allylcarbamodithioates (I) and dilauroyl peroxide (II) via a tandem radical reaction involving a 5‐exo‐trig radical cyclization as key step.

Exploring the scope of Bergman Cyclization mediated cascade reaction of alkenyl enediynes: synthesis of [5]helicene and amino acid appended [4]helicenes

Bergman Cyclization mediated cascade radical process is employed for the synthesis of [5]helicenes as well as diastereoselective mixtures of chiral amino acid appended [4]helicenes. Maximum selectivity (2.5:1) was found in case of l-leucine attached cyclic enediyne. Mechanistic considerations for this tandem radical reaction revealed that the major pathway probably involved quenching of the biradical, formed after aryl radical addition to pendant aromatic ring, by the solvent followed by aromatization. Intramolecular H-abstraction by the sp2-hybridized radical in the central ring or a 1,5-H shift followed by self-quenching could be the other possible ways to lead to the helicenes.

Synthesis of Angularly Fused Aromatic Compounds from Alkenyl Enediynes by a Tandem Radical Cyclization Process

Let's get radical: A general synthetic route toward angularly ortho-fused polyaromatic [4]helicenes starting from aryl alkenyl N-substituted cyclic enediynes is described (see scheme; DMSO=dimethyl sulfoxide, Ns=4-nitrobenzenesulfonyl). The process involved a Bergman cyclization (BC) as the key step of an unprecedented tandem radical reaction. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Carbonylative Approaches to α,β-Unsaturated Acyl Radicals and α-Ketenyl Radicals. Their Structure and Applications in Synthesis

Abstract The carbonylation of vinyl radicals gives α,β-unsaturated acyl radicals. This transformation was successfully applied to tandem radical reactions, resulting in assembling three and four components. In these reactions, both halogen abstraction from vinyl halides and hetero atom radical additions to alkynes are used to generate the parent vinyl radicals. Ab initio calculations and density functional methods predict that α,β-unsaturated acyl radicals and the isomeric α-ketenyl radicals are not canonical forms, but are isomeric species that undergo interconversion. Calculations also indicate that α,β-unsaturated acyl radicals are more stable than α-ketenyl radicals, whereas α-ketenyl radicals containing a heteroatom, such as Si, Ge, and Sn, at α-position are more stable than the corresponding α,β-unsaturated acyl radicals. This represents a promising resource for developing new synthetic applications that involve the use of the α-ketenyl radicals. Indeed, following the prediction by calculation, we succeeded in trapping of a tin-attached α-ketenyl radical by imines and amines in an intramolecular fashion. We were also able to achieve the intermolecular trapping of α-ketenyl radicals, providing a new method for alkyne carbonylation by hybrid radical/ionic reactions.

Tandem Radical Reactions

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, please click on HTML or PDF.

A Highly Diastereoselective Tandem Radical Reaction. Facile Three‐Component Routes to Protected (E)‐Polysubstituted Homoallylic Alcohols.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A highly diastereoselective Tandem radical reaction. Facile three-component routes to protected ( E)-polysubstituted homoallylic alcohols

A facile synthesis of geometrically pure ( E)-1,2,4-trisubstituted and ( E)-1,2,4-tetrasubstituted homoallylic benzoates was developed. Various Lewis acids were subsequently evaluated in the diastereoselective radical substitution of ( E)-β-nitrostyrene, and Titanium (IV) 2-ethylhexoxide emerged as the best Lewis acid in terms of yield and diastereoselectivity (up to 98% de). These reactions occurred with high regio-, diastereo- and stereoselectivity, and a possible mechanism to explain this transformation was proposed.

Tandem Radical Reactions and Ring‐Closing Metathesis. Application in the Synthesis of Cyclooctenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Tandem radical reactions and ring-closing metathesis. Application in the synthesis of cyclooctenes.

[reaction: see text] Fumarate- and acrylate-substituted oxazolidinones undergo tandem radical reaction to form dienes in moderate to good yields. The resulting dienes provide cyclooctenes in moderate to good yields after ring-closing metathesis (RCM). The role of the carbon backbone substituents and other variables in the efficiency of the eight-membered ring formation is discussed.

ChemInform Abstract: Enantioselective Tandem Radical Reactions: Vicinal Difunctionalization in Acyclic Systems with Control over Relative and Absolute Stereochemistry.

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.