Cyclopentene Annulation Research Articles

Tandem reactions in 4-siloxy-1-benzopyrylium salts: introduction of substituents and cyclohexene and cyclopentane annulation in chromones

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTandem reactions in 4-siloxy-1-benzopyrylium salts: introduction of substituents and cyclohexene and cyclopentane annulation in chromonesYong Gyun Lee, Kenji Ishimaru, Hideharu Iwasaki, Katsuo Ohkata, and Kinya AkibaCite this: J. Org. Chem. 1991, 56, 6, 2058–2066Publication Date (Print):March 1, 1991Publication History Published online1 May 2002Published inissue 1 March 1991https://doi.org/10.1021/jo00006a018RIGHTS & PERMISSIONSArticle Views615Altmetric-Citations63LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: New Formal Synthesis of (.+-.)-Estrone.

The Torgov's compound (X), which is a precursor of (±)-estrone (XI), is synthesized by a new Diels-Alder methodology forming the C-ring.

ChemInform Abstract: A Michael Alternative to Cyclopentene Annulations.

AbstractThe sulfonyloctadienone (VI), prepared from the dienoic acid (I) as shown in the reaction scheme, is subjected to base‐induced cyclization in various refluxing solvents to produce mixtures of the isomeric 3‐alkenyl‐2‐sulfonylcyclopentanones (VII) and (VIII).

New formal synthesis of (±)-estrone

(±)-Estrone is synthesised via Torgov's compound by an AB→ABC→ABCD route. The C-ring is constructed by a new Diels–Alder methodology and the D-ring by a novel cyclopentane annulation reaction from a cyclopropanol precursor.

ChemInform Abstract: Rotamer Distribution Control and Double Michael Addition for Cyclopentane Annulation with Superb Selectivity.

AbstractMichael addition of Grignard reagents (II) to (I) leads to only one enantiomer (III) as does the addition of Li salt (IV) (→ (V)).

A Michael Alternative to Cyclopentene Annulations

Abstract Intramolecular cyclopentene annulations involving carbenoidmediated cyclopropanations (Eq. 1), followed by the nucleophilic ring opening of vinylcyclopropanes have been studied extensively2 and have been applied successfully to the synthesis of triquinane terpenes.3 More recently, intermolecular [2 + 3] annulations of enones (Eq. 2), have also been studied4 and applied in the synthesis of these terpenes.5

Rotamer distribution control and double Michael addition for cyclopentane annulation with superb selectivity

Rotamer distribution control and double Michael addition for cyclopentane annulation with superb selectivity

2+3] Dihydrofuran annulation via vinyloxiranation of carbonyl compounds

Aldehydes were found to undergo facile stereoselective vinyloxiranation with the lithium dienolate of ethyl 2-bromocrotonate ( 12) at low temperature. The resulting vinyloxiranes were transformed thermolytically to functionalized dihydrofurans. An operational comparison of this heterocyclic annulation is made with its carbocyclic counterpart, the [2+3] cyclopentene annulation, and the potential for a general dihydrofuran synthesis in either a racemic or an asymmetric fashion is addressed.

Cyclopentane synthesis and annulation II: Radical cyclizations of oxathiolanones

A general procedure for the synthesis of diverse cyclopentanols via free-radical cyclization of 1,3-oxathiolan-5-ones is described. This permits the rapid assembly, by intramolecular annulation, of various ring systems for use in total synthesis.

ChemInform Abstract: Cyclopentane Synthesis and Annulation: Intramolecular Radical Cyclization of Acetals.

Abstract A general procedure for cyclopentane synthesis based on free-radical cyclization of thioacetals is described. This permits the rapid assembly, by intramolecular annulation, of various ring systems bearing useful functionality for use in total synthesis.

ChemInform Abstract: Stereocontrolled Total Synthesis of Pentalenenes via (2 + 3) and (4 + 1) Cyclopentene Annulation Methodologies.

AbstractThe preparation of pentalenene (IVa) or its epi‐isomer (IVb) is described.

Short, enantioselective synthesis of (−)-retigeranc acid via [2+3] annulation

The total synthesis of retigeranic acid 1 was achieved in 14 steps from menthene. The key features involved the vinylcyclopropanation of enone 6 with the dienolate anion of 5 to furnish vinylcyclopropane 4 and its rearrangement to pentacycle 3 in an overall [2+3] cyclopentene annulation sequence.

ChemInform Abstract: A Novel Cyclopentane Annulation Reaction: New Synthesis of Estrone.

AbstractThe key steps in the synthesis of estrone (VI) are shown in the reaction scheme.

2+3] Cyclopentene annulation and other trimethylsilyl iodide-mediated rearrangement pathways of vinylcyclopropanes

Vinylcyclopropanes of type 2 were converted to either annulated cyclopentenes of type 3 or bicyclo [3.2.1] octenes of type 4 through carefully controlled rearrangement pathways. Factors affecting these rearrangements and their utility in synthesis are described.

Cyclopentane-annelated pyranosides: a new approach to chiral iridoid synthesis

1-α-O-Methyl-loganin (1) was synthesised from methyl 2,3-anhydro-α-D-lyxopyranoside by cyclopentane annulation using the pyranose ring as the tetrahydrocoumalate skeleton.

System oriented design of triquinanes: stereocontrolled synthesis of pentalenic acid and pentalenene

Pentalenic acid, 5, and pentalenene, 4, and their C-9 epimers 5a and 4a, respectively, were synthesized using [4+1] and [2+3] cyclopentene annulation methodology. The key steps involved internal cyc1opropanation of dienes 23 or cyc1opropanation of enone 25 followed by the thermolytic rearrangements of cyclopropanes 24, 39, 42, 45, and 48 to furnish triquinanes 26 and 40. An investigation of electronic effects affecting the diradical cleavage of viny1cyclopropanes was performed. The triquinanes 26 or 40 were transformed to the title compounds by reductive operations at C-9. The equilibration of esters 60 at C-9 was briefly addressed in the context of molecular mechanics predictions regarding the thermodynamic stabilities of conformations at C-9 in the natural vs. the epi series. The stereoselectivities in approaches to natural hydrocarbons and their C-9 epimers were evaluated as better than 9:1 in each series.

Tandem Michael-carbene insertion reactions of alkynyliodonium salts. Extremely efficient cyclopentene annulations

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTandem Michael-carbene insertion reactions of alkynyliodonium salts. Extremely efficient cyclopentene annulationsMasahito. Ochiai, Munetaka. Kunishima, Yoshimitsu. Nagao, Kaoru. Fuji, Motoo. Shiro, and Eiichi. FujitaCite this: J. Am. Chem. Soc. 1986, 108, 26, 8281–8283Publication Date (Print):December 1, 1986Publication History Published online1 May 2002Published inissue 1 December 1986https://doi.org/10.1021/ja00286a037RIGHTS & PERMISSIONSArticle Views1287Altmetric-Citations133LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (354 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

New vinylcyclopropanation methodology and reagents for potential [2 + 3] cyclopentene, dihydrofuran, and pyrroline annulations

New vinylcyclopropanation methodology and reagents for potential [2 + 3] cyclopentene, dihydrofuran, and pyrroline annulations

Allylsilane-initiated cyclopentane annulations

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAllylsilane-initiated cyclopentane annulationsGeorge Majetich, Richard W. Desmond Jr., and Jose J. SoriaCite this: J. Org. Chem. 1986, 51, 10, 1753–1769Publication Date (Print):May 1, 1986Publication History Published online1 May 2002Published inissue 1 May 1986https://doi.org/10.1021/jo00360a022RIGHTS & PERMISSIONSArticle Views754Altmetric-Citations51LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts

Total Synthesis of (±)-Epiisocomenes VIA Hydrogenation of “Chatterjee's Ketone”

Abstract Dienic acid 5 was transformed into tricyclic ketone 6 in four steps using the cyclopentene annulation of dienic diazoketones. Hydrogenation of 6 under several conditions yielded ketone 7a which was further transformed into β-epiisocomene 4 and epiisocomene 3, contrary to the results previously reported by Samir Chatterjee.