Vinyl Ketene Research Articles

Regioselective polymerization of vinyl ketene cyclic acetal by means of cationic initiators

The polymerization of 4-phenyl-2-propenylidene-1,3-dioxolane with various cationic initiators is investigated. It is found that polymerization with BF 3 , trifluoromethanesulfonic acid or SnCl 4 as an initiator gives a polymer with almost complete 3,4-polymerization structure containing the 3,7-polymerization structure as an irregular structure. The polymerization with I 2 or AlCl 3 completely proceeds through the 1,7-polymerization to yield an insaturated polyester with a trans structure

ChemInform Abstract: Stereoselection in the Chromium‐Mediated Intramolecular (2 + 2) Cycloadditions of Vinyl Ketenes and Alkenes.

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.

Stereoselection in the chromium mediated intramolecular [2 + 2] cycloadditions of vinyl ketenes and alkenes

The first study of the relative diastereoselectivity of the intramolecular [2+2] cycloadditions of alkenes and vinyl ketenes generated from the reactions of carbene complexes with chiral enynes is reported

Synthesis and reactivity of iron tricarbonyl complexes of vinyl ketenes, vinyl ketenimines and vinylallenes

Abstract

Studies towards the synthesis of obtusenyne. A Claisen rearrangement approach to unsaturated nine-membered lactones.

An advanced intermediate for the synthesis of the Laurencia oxonane natural product obtusenyne 1. namely the unsaturated nine-membered lactone 3, was efficiently prepared in seven steps from ( E)-3-hexenoic acid 7. The key transformation was the Claisen rearrangement of the vinyl ketene acetal 4, which represents novel methodology for the preparation of such unsaturated nine-membered lactones.

Gemischt ionisch und elektronisch leitende derivate des polyvinylalkohols

By reacting poly(vinylalcohol) with elemental bromine in aqueous solution a partially oxidized copolymer of vinyl alcohol, β-bromo-vinyl alcohol, ketene, and bromo-ketene units obtained, which on treatment with aqueous alkali hydroxide yield salts with electric and ionic conductivity ( K 140°C⩽10 −3S cm −1).

Enantiomerically pure vinyl ketene acetals as dienes in the Diels-Alder reaction

Enantiomerically pure vinyl ketene acetals as dienes in the Diels-Alder reaction

ChemInform Abstract: Intramolecular (2 + 2)Cycloadditions of Ketenes and Vinyl Ketenes to Olefins. Part 3. The Synthesis of Angular Anellated Triquinane Derivatives.

AbstractThe cyclopentenecarboxamide (I) is substituted to give the homoallylic derivative (III) which is converted to the acid chloride (IV).

ChemInform Abstract: Type II Intramolecular (2 + 2)Cycloadditions of Alkenes with Alkylvinylketenes. Synthesis of Methyl Jasmonate.

AbstractAddition of the acid chloride (I) to a solution of triethylamine in toluene at reflux temperature results in the formation of the bicycloheptanone (III) and the by‐products (IV) and (V) via the vinyl ketene (II).

Interrelationship between carboxyvinylketenes, methyleneketenes, vinylketenes, and hydroxyacetylenes

Carboxy(vinyl)ketenes, alkylideneketenes, and vinylketenes have been obtained selectively, sequentially, and isomerically pure for the first time by flash vacuum pyrolysis of 2,2-dimethyl-5-alkylidene-1,3-dioxane-4,6-diones (Meldrum's acid derivatives) under controlled conditions. Each of the ketenes was directly observed by IR spectroscopy and trapped with methanol or aniline. Highly unstable compounds believed to be the hydroxyacetylene isomers of the alkylidene- and vinylketenes have been observed for the first time.

ChemInform Abstract: Periselectivity in Cycloadditions to Vinyl Methyl Ketene and Structurally Related Vinyl Ketene Imines.

AbstractThe vinylic ketenes or ketene imines (I) react with strongly electrophilic agents such as tetracyanoethylene (II) or phenyltriazolinedione (IV) to yield the 1,4‐cycloadducts (III) or (V).

Synthesis of (±)-ramulosin via inverse type hetero-diels-alder reaction 1

Condensation of 4-formylbutanoates ( 4a , b ) with phenyl-thioacetone ( 5 ) provided the 1-oxa-1,3-diene derivatives 6a , b which afforded in high yielding inverse type hetero-Diels-Alder' reactions with vinyl ethers and ketene acetals the desired dihydropyran cycloadducts 7a - c and 11a - c , respectively. The target molecule (±)-ramulosin I was obtained from compounds 11a and 7a inconvenient chemo- and diastereoselective three and four step transformations.

ChemInform Abstract: Synthesis of Terpenes Containing the Bicyclo(3.1.1)heptane Ring System by the Intramolecular (2 + 2)Cycloaddition Reaction of Vinyl Ketenes with Alkenes. Preparation of Chrysanthenone, β‐Pinene, β‐cis‐Bergamotene, β‐trans‐Bergamotene, β‐Copaene, and β‐Ylangene and Lemnalol.

ChemInformVolume 18, Issue 39 Natural Products ChemInform Abstract: Synthesis of Terpenes Containing the Bicyclo(3.1.1)heptane Ring System by the Intramolecular (2 + 2)Cycloaddition Reaction of Vinyl Ketenes with Alkenes. Preparation of Chrysanthenone, β-Pinene, β-cis-Bergamotene, β-trans-Bergamotene, β-Copaene, and β-Ylangene and Lemnalol. Y. S. KULKARNI, Y. S. KULKARNI Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this authorM. NIWA, M. NIWA Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this authorE. RON, E. RON Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this authorB. B. SNIDER, B. B. SNIDER Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this author Y. S. KULKARNI, Y. S. KULKARNI Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this authorM. NIWA, M. NIWA Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this authorE. RON, E. RON Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this authorB. B. SNIDER, B. B. SNIDER Dep. Chem., Wayne State Univ., Detroit, MI 48202, USASearch for more papers by this author First published: September 29, 1987 https://doi.org/10.1002/chin.198739276AboutPDF 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 onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume18, Issue39September 29, 1987 RelatedInformation

ChemInform Abstract: Intramolecular (4 + 2) Cycloadditions of (Z)‐α,β‐Unsaturated Aldehydes with Vinyl Sulfides and Ketene Dithioacetals.

AbstractThe E/Z isomers (VII) and (VIII) are prepared from (I) by stereoselective olefination of the common intermediate (IV) using either (V) or (VI).

ChemInform Abstract: Preparation of 7‐Methyl‐7‐vinylbicyclo(3.2.0)heptene via Cyclobutanone Reduction.

AbstractThe isomeric cycloadducts (I) of cyclopentadiene and methyl vinyl ketene are converted to the hydrazones (II) which undergo Wolff‐Kishner reduction, yielding a mixture of the exo‐ and endo‐vinylbicycloheptenes (III).

Intramolecular [4 + 2] cycloadditions of (Z)-.alpha.,.beta.-unsaturated aldehydes with vinyl sulfides and ketene dithioacetals

Preparation du methyl-2 methylthio-8 octadiene-2,7al et etude de sa cyclisation intramoleculaire. On etudie egalement la cyclisation intramoleculaire du α,δ-dimethyl dithianne-1,3-Δ2:ω-heptene-2al

ChemInform Abstract: Stereoselective Deprotonation of α,β‐Unsaturated Amides. γ‐Silylated α,β‐Unsaturated Amides. Formation by [1,5]Silicon Migration from O‐Silylated Vinyl Ketene Aminals and Fluoride‐ and Lewis Acid‐Mediated Aldol Condensations.

AbstractAus den ungesättigten Amiden (I) erhält man nach Metallierung die isomeren Methylierungsprodukte (II)‐(IV).

Unsaturated ketenes: A study of their formation and rearrangement by tandem mass spectrometry and low‐temperature infrared spectroscopy

AbstractA combination of collisional activation mass spectrometry and low‐temperature infrared spectroscopy has been used to monitor the production and isomerization of vinyl‐ and methylene‐ketenes. Vinyl‐ and 2‐propenyl‐ketenes were produced by flash vacuum pyrolysis of β,γ‐unsaturated acid chlorides. Vinyl(carboxyl)ketenes, vinylketenes and methyleneketenes were obtained from Meldrum's acid derivatives (5‐alkylidene‐1,3‐dioxane‐4,6‐diones). The formation of methyleneketenes by pyrolysis of α, β‐unsaturated acid chlorides is only indicated in the mass spectrometry experiments. Carbonylcyclopropane was obtained by pyrolysis of cyclopropylcarbonyl chloride or the corresponding Meldrum's acid derivative. The methyleneketenes isomerize to vinylketenes in the gas phase, particularly under conditions involving long contact times. Carbonylcyclopropane thermally decarbonylates to allene, not methylacetylene. Molecular ions of vinylketenes are obtained via pyrolysis of either acid chlorides or Meldrum's acid derivatives. Molecular ions of alkylmethyleneketenes are obtained pure only by electron impact induced fragmentation of Meldrum's acid derivatives.

A new synthesis of eight-membered lactones containing a 5,6-double bond

Claisen rearrangement of the vinyl ketene acetals (7; a, R = CH2OSiPh2 But, or b, R = n-pentyl) which are generated in situ by syn-elimination of the corresponding selenoxides (6a,b) in refluxing xylene gave the eight-membered lactones (8a,b).

γ-Silylated α,β-unsaturated amides. Formation by [1,5] silicon migration from O-silylated vinyl ketene aminals and fluoride- and Lewis acid-mediated aldol condensations

O-Silylated vinyl ketene aminal 2, obtained from lithiated unsaturated amide 1, undergoes a thermal [1,5] silicon migration to give γ-silylated product 3b which participates in fluoride- and titanium tetrachloride-mediated aldol condensations to give adducts 5 in poor and excellent syn diastereoselectivity respectively.