The Reaction of Patchoulol with Lead Tetraacetate,a Regiospecific Fragmentation

Patchoulol (1) forms 2,2,6,8-tetramethylbicyclo [5.3.1]undec-7-en-3-one (5) with lead tetraacetate. This ketone undergoes acid-catalyzed cyclization to 2,6,6,10-tetramethyltricyclo [5.3.1.0^1,5]undec-9-en-5-ol (10) , and is reduced to 2 stereoisomeric alcohols with lithium aluminium hydride. One of these alcohols 8 is readily dehydrated with cyclization to 2,6,6,10-tetramethyltricyclo [5.3.1.0^1,5]undec-9-ene (12) and a double bond isomer 13 , longer treatment with acid resulting in a Wagner-Meerwein rearrangement to a mixture of two 1,3,7,7-tetramethyltricyclo [6.2.1.0^2,6]-undecenes ( 19 and 20 ), isomeric with β-patchoulene ( 23 ). The other alcohol 7 with p-toluenesulfonic acid forms the cyclic ether, 1,3,7,7-tetramethyl-11-oxatricyclo-[4.4.1.1^2,8]dodecane ( 15 ).     

The Reaction of Norbornene with Lead Tetraacetate and Thallium Trinitrate. Preliminary communication

The reaction of norbornene with lead tetraacetate is found to be much more complex than previously reported. In acetic acid and in benzene, the syn-7-norbornenyl, 3-nortricyclyl, and syn and anti-7-acetoxy-exo-2-norbornyl acetates were characterized. In methanol, the isolated products represented most of those expected from the competition of methanol and acetate in the neutralization of the intermediate carbocations. The reaction of norbornene with thallium trinitrate in the above solvents yielded very complex mixtures besides the above mentioned products which were formed in about 50% yield.     

Selective Oxidations with Lead Tetraacetate; A Convenient Preparation of 3-Methoxy-4-iso-Propylbehzylalcohol

Literature reports several examples of oxidation of alkylaromatics with lead tetraacetate and its applications in synthetic organic chemistry^1–3. However, there are no systematic studies dealing with preferential oxidation of methyl groups attached to aromatic rings. Investigations presented here show that lead tetraacetate oxidation of aromatic compounds having low ionization potential can lead to preferential oxidation of methyl groups attached to aromatic rings and this selectivity in oxidation has been employed to effect a convenient synthesis of 3, an intermediate in the synthesis of sempervirol⁴.     

A Novel Oxidative N-Demethylation of 12-Membered Macrolide with Lead Tetraacetate

Erythromycin has been extensively used in the treatment of bacterial infections for over 50 years1. In addition to the antimicrobial effect, the quite unique antiinflammatory activity of the erythromycin derivatives has attracted much attention as new the…     

Mild Oxidative Bromination of Alkenes and Alkynes with Zinc Bromide and Lead Tetraacetate

Abstract

Zinc bromide and lead tetraacetate is a practical and safe source of bromine. The combined reagents are used to brominate a variety of alkenes to vicinal dibromoalkanes. Similarly, alkynes can be converted into dibromoalkenes in high yields. The reagents are also capable of tetrabromination of alkynes.     

A Convenient Synthesis of Diacyl Selenides by Selenium Transfer Reaction of Primary Selenoamides

Aryl selenoamides are rather interesting compounds because they are versatile intermediates in organic chemistry1. It was reported that selenobenzamides have been used as selenium transfer reagents in the synthesis of alkyl diselenides from reactive halides2. We began to investigate the reactivity of arylselenoamides toward acyl chlorides and guess that this reaction would produce acyl diselenides. In surprise we could not find the diacyl diselenides (Scheme 1). Instead diacyl selenides a…     

β-Diketone Synthesis by Reaction of α-Haloketones with Acid Chlorides or Acid Anhydrides Promoted by Samarium Triiodide

Promoted by SmI₃, α-haloketones were reacted with acid chlorides or acid anhydrides and β-diketones were synthesized via intermediate samarium enolates.     

Allylic Oxidation of some 5,6-Unsaturated Steroids with Lead Tetraacetate. Communication XXII on reactions with lead tetraacetate

Oxidation of cholesteryl acetate and diosgenyl acetate with lead tetraacetate in benzene or glacial acetic acid solution results in allylic acetoxylation in the C-7 position. These reactions are nonstereospecific, and in both solvents mixtures of the corresponding 7β- and 7α-epimeric acetoxy derivatives are formed. On the basis of the results, the mechanism of this oxidation reaction is discussed.     

一种新方法合成荧光β-二酮铜(Ⅰ)配合物(英)

At room temperature, the reducing reaction between the bis(diphenylphosphino)butane (dppb) ligand and the compound [Cu(tfac)₂] (tfac=2-thenoyltrifluoroacetone) gave luminescent copper(Ⅰ) complex [Cu(dppb)(tfac)]₂. They have been characterized by physicochemical and spectroscopic methods. Crystal structure of the title complex shows that 2-thenoyltrifluoroacetone behaves as chelating ligand and dppb coordinates as bridging bidentate ligand to Cu(Ⅰ) atoms in the newly prepared copper(Ⅰ) complex. The crystal is monoclinic, space group P2₁/n, with cell parameters a= 1.031 0(2) nm, b= 1.8730(4) nm, c= 1.7630(4) nm, β = 95.10(3)°, Z = 4, V= 3.391 0(12) nm³, R= 0.060 3, wR= 0.1434. CCDC: 228393.     

Thermochemical Reaction of Lead Oxide with a Polytetrafluoroethylene Matrix

Russian Journal of Applied Chemistry - Thermochemical transformations that lead oxide used as filler in a polytetrafluoroethylene matrix undergoes in the course of heat treatment were studied....     

Reaction of 1,2-dichloroiodotrifluoroethane with zinc

The zinc coupling reaction of 1,2-dichloroiodotrifluoroethane (I) in acetic anhydride-methylene chloride has been reinvestigated in more detail than its original disclosure. The expected coupling product C₄F₆Cl₄ was shown to be an isomeric mixture of three components, CF₂ClCFClCFClCF₂Cl (II, 80%), CFCl₂CF₂CF₂CFCl₂ (IIa, 15%) and CF₂ClCFClCF₂CFCl₂ (IIb, 5%). In addition, other products e.g. CF₂CFCl, C₆F₉Cl₅ and C₈F₁₂Cl₆ were formed in minor quantities. A probable mode of formation of the various byproducts via initial formation of CF₂CFCl and subsequent telomerization is presented.     

Reaction of Chlorophosphazenes with 1,2-Epoxides

Studies on the reaction of chlorophosphazenes with 1,2-epoxides with a catalyst, in the presence or absence of solvent, are discussed. The physicochemical properties of the obtained chlorophosphazenes are described as well as the results of infrared spectroscopic measurements and examination of thermal properties.     

Reaction of 1,2-dichloroidotrifluoroethane with zinc

After publication of the above paper, the possibility of the presence of an isomeric iodide, 2,2-dichloroiodotrifluoroethane, in the title compound when prepared by the addition of ICI to chlorotrifluoroethylene, was pointed out by Dr. R. E. Banks of the University of Manchester Institute of Science and Technology, Manchester, U.K. The title compound was purchased from a commercial source and on enquiry we learned that it was indeed prepared by the addition of ICI to chlorotrifluoroethylene at sub-ambient temperature. Even though the compound had been subjected to routine Gas Chromatographic analysis before work was started and we could not detect more than one component, we subsequently examined it by ¹⁹F NMR. The results showed that it was contaminated by ∼ 19% of the isomeric iodide. We deeply regret this oversight and thank Dr. Banks for pointing out the possibility. The presence of this isomer can explain the formation of CFC1₂CF₂CFC1₂ and CF₂C1CFC1CF₂CFC1₂ among the products we observed, though it alone cannot possibly account for the formation of chlorotrifluoroethylene, C₆F₉C1₅ and C₈F₁₂C1₆. Further work is in progress and will be communicated at a future date. will be communicated at a future date.     

Graft Copolymerization of Benzyl Methacrylate onto Poly(Acryloyl-L-valine) Microspheres by Using the Photoreaction of Side Carboxyl Groups with Lead Tetraacetate

N-Acryloyl-L-valine (ALV) was found to yield polymer microspheres when it was polymerized with a radical initiator in acetophenone. The resulting microspheres showed thermochromism in aromatic solvents such as benzonitrile, methyl benzoate, and acetophenone. Graft copolymerization of benzyl methacrylate (BzMA) onto poly(ALV) microspheres was carried out in benzonitrile by using the photoreaction of carboxyl groups in poly (ALV) with Pb(OAc)₄. The grafting efficiency was not very high (15–28%). Methyl methacrylate as the second monomer gave a higher grafting efficiency (56%) although the polymer yield was considerably lower. The resulting graft copolymer was characterized by IR spectroscopy and thermogravimetry. The grafted poly (ALV) microspheres were well dispersed in benzene. A benzene solution of grafted poly(ALV) microspheres and homopoly(BzMA) gave a film with finely dispersed poly (ALV) microspheres.