Reactions Of Lead Tetra-acetate Research Articles

Solid‐Phase Oxoalkylation of Pyridines and Quinolines with 1‐Methylcycloalkanols under the Action of Lead Tetraacetate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

ChemInform Abstract: Solid‐Phase Reactions of Lead Tetraacetate with Tertiary Cycloalkanols and Pyridine.

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Solid-phase oxoalkylation of pyridines and quinolines with 1-methylcycloalkanols under the action of lead tetraacetate

A new procedure was developed for the introduction of the oxoalkyl fragment into N-heteroaromatic compounds of the pyridine and quinoline series. The procedure is based on the solid-phase reactions of lead tetraacetate with aromatic N-heterocycles and tertiary cycloalkanols.

Solid-phase reactions of lead tetraacetate with tertiary cycloalkanols and pyridine

Solid-phase reactions of lead tetraacetate with tertiary cycloalkanols and pyridine

Sonochemical Reactions of Lead Tetraacetate with 4-Substituted Styrenes

Abstract A good linear free energy relationship was observed between the radical reactivity of the sonochemical reactions of 4-substituted styrenes with lead tetraacetate and the vapor pressure of the styrenes, indicating a probable control of the process by an intra-bubble activation.

Electrophilic metal-alkyl bond cleavage in tetraorganosilicon and tetraorganotin compounds by lead tetracarboxylates and aryllead tricarboxylates

Methyl-silicon bond cleavage of tetramethylsilane occurs with aryllead(IV) tricarboxylates in trifluoroacetic acid to produce aryl(methyl)lead(IV) bistrifluoroacetates in high yield. An extension of the study to tetraalkylstannanes has shown that alkyl-tin cleavage by lead(IV) carboxylates proceeds even in chloroform, while a detailed study of the reactions of lead tetraacetate with tetraalkylstannanes indicated the reaction to be an electrophilic cleavage rather than one involving an electron transfer mechanism.

Mechanism of sonochemical excitation in the reactions of lead tetraacetate with some organic substrates

Strikingly contrasting positive and negative sonochemical effects were observed in the reactions of lead tetraacetate with styrene and 2-octanol, respectively. The decomposition of lead tetraacetate itself in the absence of a substrate is not accelerated by ultrasound. These results are consistent with the idea that the radical chain reaction of lead tetraacetate and styrene involves the bimolecular initiation step of the two species; under ultrasonic irradiation, styrene is excited in the gas phase of the cavity. The efficiency of the sonochemical excitation must be decisively different between the gas phase and the liquid shell of the cavity. The importance of the boiling point of a substrate involved in the radical initiation step is proposed as a hypothetical guideline in homogeneous sonochemistry.

The Site of the Sonochemically-Initiated Radical Reaction of Lead Tetraacetate with β-Methylstyrene

Abstract The effective temperature of the radical propagation step of the ultrasonically accelerated reaction of lead tetraacetate with β-methylstyrene was thermodynamically determined as close to the ambient temperature of the bulk liquid.

ChemInform Abstract: Reaction of Lead Tetraacetate with Cholest‐5‐ene and Its 3β‐Substituted Derivatives.

Chemischer InformationsdienstVolume 17, Issue 11 Natural Products ChemInform Abstract: Reaction of Lead Tetraacetate with Cholest-5-ene and Its 3β-Substituted Derivatives. SHAFIULLAH SHAFIULLAH, SHAFIULLAH SHAFIULLAHSearch for more papers by this authorM. R. ANSARI, M. R. ANSARISearch for more papers by this authorSHAMSUZZAMAN SHAMSUZZAMAN, SHAMSUZZAMAN SHAMSUZZAMANSearch for more papers by this authorB. Z. KHAN, B. Z. KHANSearch for more papers by this author SHAFIULLAH SHAFIULLAH, SHAFIULLAH SHAFIULLAHSearch for more papers by this authorM. R. ANSARI, M. R. ANSARISearch for more papers by this authorSHAMSUZZAMAN SHAMSUZZAMAN, SHAMSUZZAMAN SHAMSUZZAMANSearch for more papers by this authorB. Z. KHAN, B. Z. KHANSearch for more papers by this author First published: March 18, 1986 https://doi.org/10.1002/chin.198611342AboutPDF 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. Volume17, Issue11March 18, 1986 RelatedInformation

Reaction of Lead Tetraacetate with Cholest-5-ene and its 3β-Substituted Derivatives

Reaction of Lead Tetraacetate with Cholest-5-ene and its 3β-Substituted Derivatives

The reaction of lead tetraacetate with hydrocarbons

The free radical reaction of lead tetraacetate with hydrocarbons has been investigated. The products of these reactions are the acetate esters. The hydrogen abstracting species from lead tetraacetate is found to have a primary to secondary to tertiary selectivity of 1:27:123 based upon relative reactivities.

ChemInform Abstract: THE REACTION OF LEAD TETRAACETATE WITH 3β‐HYDROXY STEROIDS

Abstract3β‐Hydroxysteroide wie z.B. die Verbindungen (I) und (III) mit elektronegativer Substitution der 5a‐Stellung werden durch Bleitetraacetat in Gegenwart von Calciumcarbonat und einer Spur Benzoylperoxid zu 3β,19‐Oxidosteroiden (II) und (IV) oxidiert.

The reaction of lead tetraacetate with 3.BETA.-hydroxy steroids.

It was found that the reaction of lead tetraacetate with 3β-hydroxy steroids of the 5α-series gave the corresponding 3β, 19-oxido steroids. Only poor yields were obtained in the cases of 3β-hydroxy steroids having no substituent at C-5 (5α-H). Substitution at the 5α-position by an electronegative group such as halogen or acetoxyl enhanced the yield of the 3β, 19-oxido compound. The best result was obtained when a steroid was heated with lead tetraacetate in benzene in the presence of calcium carbonate and a trace of benzoyl peroxide.

Bislactonization of unsaturated diacids using lead tetraacetate

The reaction of lead tetraacetate with unsaturated carboxylic acids (or salts) to from bislactones (γ or δ) can be controlled to produce efficiently cis addition of two carboxylic oxygens to the double bond, in consonance with an initial plumbolactonization step followed by S N2 displacement of lead.

Conformations of the 10‐membered Ring in 5, 10‐Secosteroids. II. (E)‐3α‐Acetoxy‐5, 10‐seco‐1 (10)‐cholesten‐5‐one and (E)‐5, 10‐seco‐1 (10)‐cholestene‐3, 5‐dione

Abstract(E)‐3α‐Acetoxy‐5, 10‐seco‐1(10)‐cholesten‐5‐one (3) was synthesized by fragmentation of 3α‐acetoxy‐5α‐cholestan‐5‐ol (1) using the photochemical version [3] of the lead tetraacetate reaction [4], and transformed into the corresponding 3‐oxo‐compound (5). Two conformations (A and B) were deduced for the 10‐membered ring of 3 by analysis of the 1H‐ and 13C‐NMR. spectra in toluene. The major conformation (A) corresponds to that found in the solid state by X‐ray analysis. According to its NMR. spectra in toluene, the medium‐sized ring of the diketone 5 exists also predominantly in two conformations, the major one being analogous to A (the solid‐state conformation of the 3β‐acetoxy isomer (9) [1]) and the minor one to A (see above). The stereochemistry of the acidcatalyzed and thermal cyclisations of 3 as well as of the corresponding 5‐oxime is discussed in terms of conformational factors.

Vicinal phenyl group shift in the lead tetraacetate and related oxidations of 5,5,5-triphenyl-1-pentanol

In the lead tetraacetate and heavy metal-bromine oxidations of 5,5,5-triphenyl-1-pentanol 1d, the major cyclization product obtained was the rearranged 2,2,3-triphenyltetrahydro-2 H-pyran 11d, resulting from homolytic and heterolytic 1,2-phenyl group shift (the latter only in the lead tetraacetate reaction) in the respective intermediate species with electron deficient δ-carbon 4d and 6d.

The mechanism of the reaction of lead tetraacetate–hydrogen fluoride with 1-octene

The reaction of 1-octene with the lead tetraacetate–hydrogen fluoride reagent led to products resulting from the Markovnikov addition of lead and its ligand (fluoro or acetoxy) to the olefinic double bond. Displacement of lead from the organometalic intermediate via three separate pathways could be distinguished; displacement concomitant with hydride migration alkyl migration, or direct displacement by an external ligand. The pathways for the formation of the product difluorides, fluoroacetates, and diacetate could be followed by an analysis of the products obtained from carrying out the reaction using 1-octene-1-13C as substrate. The major pathways to product formation resulting from either hydride or alkyl migration could be rationalized as proceeding through the intermediacy of a resonance stabilized α-fluorocarbonium ion.

The lead tetraacetate reaction of alcohols containing a small ring. Part II. Cyclobutane‐methanols and cyclopropane‐ethanols

AbstractThe leadtetraacetate and lead tetraacetate/metal chloride oxidations of cyclobutane‐methanol, cyclopropane‐ethanol and the corresponding α, α‐diniethyl alcohols have been investigated and compared with the oxidative reactions of cyclobutane‐carboxylic acid, cyclopropane‐acetic acid and 4‐pentenoic acid, performed with the same reagents and under similar conditions. It was found that alcohol β‐fragmentation and acid decarboxylation follow a remarkably similar mechanistic course, affording comparable results when the substrates are of the same structural type (1, 2 and 5; 3, 4 and 6) or are converted to the same intermediate alkyl radical fragments (3, 4, 6 and 7). In addition, cyclization products formed from cyclopropane‐ethanol (dihydropyran derivative 31) and 4‐penteuoic acid (γ‐lactones 38) have been isolated and identified.

Oxidative decarboxylation of dicarboxylrc acids by lead tetraacetate and oxidation of generated carboxyalkyl radicals by Pb(IV) and Cu(II) carboxylates

1. The reaction of lead tetraacetate with dicarboxylic acids of general formula RCH2CH(COOH)(CH2)n-COOH (R=Alk, n=1, 2, 3 or 10) in the presence of pyridine led to their selective oxidation decarboxylation and the generation of carboxyalkyl radicals RCH2ĊH(CH2)COOH. In a similar manner, the 1-(carbomethoxymethyl)nonyl and 2-carbomethoxycyclohexyl radicals were obtained from the monomethyl esters of the 2-octylsuccinic and cyclohexane-1,2-dicarboxylic acids. 2. The main products when the radicals are oxidized with the Pb(IV) and Cu(II) carboxylates are alkenoic acids and their esters, γ- and δ-laetones (in the oxidation of the carboxylalkyl radicals with n = 2 and 3), and esters of acetoxy-substituted monocarboxylic acids (when oxidation is with Pb(IV) carboxylates). 3. The carboxy and carbomethoxy groups in the 2- and 3-carboxy- and 2-carbomethoxyalkyl radicals direct the oxidativeΒ-deprotonation of these radicals under the influence of copper ions predominantly toward the formation of alkenoic acids or of their esters, where the double bond is further away from the functional group.

Reaction of lead tetra-acetate with aldehyde nitrophenylhydrazones

Oxidation of aliphatic aldehyde 2-nitrophenyl- or 2,4-dinitrophenyl-hydrazones with lead tetra-acetate is exceptional, giving azo-acetates containing α-hydrogen atoms as major products. Lesser yields of the expected diacylhydrazine products are also formed in a competing reaction. The yields of these diacylhydrazines increase, at the expense of the azo-acetates, with increasing chain length of the aliphatic substituent at the methine carbon atom of the hydrazone. Aliphatic aldehyde 4-nitrophenylhydrazones and benzaldehyde 2-nitro- and 2,4-dinitrophenylhydrazones behave normally, giving diacylhydrazines.