Lead Tetraacetate Oxidation Research Articles

Kinetic Evidence for Steric Enhancement of Resonance in Vanadium(V) and Lead Tetraacetate Oxidation of Substituted Phenyl Methyl Sulphides

Kinetic Evidence for Steric Enhancement of Resonance in Vanadium(V) and Lead Tetraacetate Oxidation of Substituted Phenyl Methyl Sulphides

ChemInform Abstract: Polarized Ketene S,S‐ and S,N‐Acetals. Part 67. Lead Tetraacetate Oxidation of α‐Oxoketene S,N‐ and N,N‐Acetals.

ChemInform Abstract: Polarized Ketene S,S‐ and S,N‐Acetals. Part 67. Lead Tetraacetate Oxidation of α‐Oxoketene S,N‐ and N,N‐Acetals.

ChemInform Abstract: Polarized Ketene S,S‐ and S,N‐Acetals. Part 52. Lead Tetraacetate Oxidation of 3‐Anilino‐3‐methylthio‐2‐arylacrylonitriles. A Novel Approach to Substituted Indoles (III).

AbstractIn contrast to the intermediates (IIa) and (IIe), the products (IIb)‐(IId) are unstable.

Polarized ketene S,S- and S,N-acetals. Part 52. Lead tetra-acetate oxidation of 3-anilino-3-methylthio-2-arylacrylonitriles. A novel approach to substituted indoles

Lead tetra-acetate oxidation of 3-anilino-3-methylthio-2-phenylacrylonitrile (4a) gave the iminoacetate (5a) and 3-cyano-2-methylthio-1-phenylindole (6a). The corresponding methoxy substituted 2-arylacrylonitriles (4b–d), however, yielded the symmetric dimeric products (7a–c) and the unstable iminoacetates (5a–d) respectively under similar conditions. The corresponding p-chloro derivative (4e) afforded the stable iminoacetate (5e), dimer (7d), and 6-chloroindole (6e) in low yields. The iminoacetates (5a–e) could be cyclized to the respective indoles (6a–e) in the presence of boron trifluoride–diethyl ether. The probable mechanistic pathways for the formation of various products are described.

Studies on lead tetraacetate oxidation of α -oxoketene S,N- and N,N-acetals 1

Lead tetraacetate oxidation of α-oxoketene-S,N-phenyl ( 1a ) and S,N-benzyl ( 1b ) acetals gave the iminoacetate 2 and α-acetoxy-S,N-acetal 3 respectively, while the corresponding S,N-ethylacetal 1c yielded the iminodiacetate 5 . The corresponding N,N-arylacetals 7a - d afforded the respective 2-N-aryl-3-(arylimino)-5-aryl-4-isoxazolines 8a - d under similar conditions via oxidative cyclization. The oxidation of N,N-(4-methylphenyl)acetal 7e gave 3-benzoyl-5-Bethyl-2-(4-methylphenylamino)-indole 9a , iminodiacetate 10 and the dimeric indole 11 , besides the corresponding 3-(4-methylphenyl-imino) isoxazoline 8e in varying yields. The N,N-(2-methylphenyl) acetals 7f and 7g afforded under similar conditions the respective 3-(2-methylphenylimino)isoxazolines 8f , 8g and the indoles 9b , 9c in good yields. The structural assigment and the probable mechanism of the formation of all the products have been discussed.

Lead tetraacetate oxidation of (Z)‐ and (E)‐5, 10‐Secocholest‐1 (10)‐ENE‐3β,5α−Diol 3‐acetate1

AbstractThe lead tetraacetate oxidation of (Z)‐5, 10‐secocholest‐1(10)‐ene‐3β,5α−diol 3‐acetate (1) gave products arising from: (i) conversion of the 5α−hydroxy group to the ketone function (2), (ii) intramolecular cyclization (to the 2α,5α−tetrahydrofurane‐type ether 3), and (iii) allylic acetoxylation at the C(9) position (3 and 4), while similar oxidation of (E)‐5, 10‐secocholest‐1 (10)‐ene‐3β,5α−diol 3‐acetate (5) afforded mainly the product formed by conversion of 5α−OH to the keto‐carbonyl group (6).

ChemInform Abstract: Studies on Pyridopyrimidines. Part 1. Synthesis of Pyrazolo(3′,4′:4,5)pyrido(2,3‐d)pyrimidine Derivatives.

AbstractThe fused pyrimidines (VI) are obtained by intramolecular 1,3‐dipolar cycloaddition reaction of the intermediate nitrile imides (V), generated by lead tetraacetate oxidation of the tosylhydrazones (IV).

苦味物質Ａｍａｒｏｌｉｄｅの全合成

Amarolide, one of the representative quassinoids, is a tetracyclic terpenoid having a picrasane skeleton with 10 chiral centers. The first total synthesis of (±) -amarolide has been accomplished stereoselectively from a known tricyclic compound.Orthoester Claisen rearrangement and lead tetraacetate oxidation were utilized as key reactions to prepare 12β-hydroxypicrasan-3-one, a compound which has the correct relative stereochemistry of all the six ring-juncture chiral centers of the picrasane skeleton.This 12β-hydroxypicrasan-3-one was transformed into (±) -amarolide by 18 steps reactions, including the 1, 3-carbonyl transposition reactions, introduction of two hydroxyl groups at C-2 and C-11 positions, respectively, and an oxidation of the ether ring to afford δ-lactone.The NMR spectral data of synthetic amarolide and its diacetate were completely identical with those of natural ones. Overall yield of this synthesis of (±) -amarolide from the known tricyclic compound by 35-step reactions was 0.2%.As the transformation of amarolide into quassin has already been known, this synthesis constitutes also a formal synthesis of (±) -quassin.

Synthesis and Reactions of 3‐Phenyl‐3,4‐Dihydro‐1, 4‐Quinoxalin‐2 (1H) ‐One and its Heterocyclic Analogues

AbstractThe lactams quinoxalinone 3a, benzothiazinone 3b and benzothiazinone 3c were synthesized by reactions of methyl 2‐bromo‐2‐phenylethanoate 1 with orthosubstituted arylamines 2a ‐ 2c. Subsequent reductive alkylation of the lactams with sodium hydride and iodomethane afforded only the N‐alkylated quinoxalinone 4a and benzothiazinone 4b. Lithium aluminium hydride reduction of the lactams 3a‐3c gave the dihydro‐derivatives 5a, 5b and 5c while similar reduction of the N‐alkylated lactams 4a and 4b yielded the unsaturated quinoxaline 6a and benzothiazine 6b respectively. Lead tetraacetate oxidation of the quinoxalinone 3a furnished the unsaturated quinoxalinone 9 which was N‐alkylated using sodium borohydride in formic acid to give 10. Treatment of the lactams 3a, 3b and 3c with phosphorus pentasulphide produced only the quinoxalinethiol 11 and benzothiazinethione 12. Compounds 11 and 12 were alkylated with iodomethane and sodium ethoxide to give the S‐alkylated products 13 and 14 respectively.

ChemInform Abstract: Addition of Phthalimidonitrene to Acetylenic Fatty Acid Esters: Synthesis of Long‐ Chain 2‐Phthalimido‐2H‐azirines.

AbstractDie im Titel genannten Verbindungen (III) bzw. (IV) werden auf dem skizzierten Weg hergestellt.

ChemInform Abstract: The Conversion of Primary Alcohols to the Corresponding Aldehydes by a Modified Lead Tetraacetate Oxidation.

AbstractAus den A1koho1en(I) erhält man durch Oxidation mit Bleitetraacetat und Mangandiacetat die Aldehyde (II) in guten Ausbeuten.

Synthesis of the 3-acetoxy-7-oxo-1-azabicyclo [3.2.0] hept-2-ene-2-carboxylate system

Lead tetraacetate oxidation of the carbapenem derived ethanethiol adducts (4–6) gave the corresponding 3-acetoxy-3-ethylthio derivatives (7–9). Oxidation to sulphone and elimination of ethylsulphinic acid furnished the 3-acetoxy-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate ester (12). Alternatively, elimination of acetic acid from (7) and (8) provided a new route to alkylthiocarbapenems.

Studies on tetrahydroisoquinolines. XXVIII Syntheses of (.+-.)-N-methyllaurotetanine, (.+-.)-cassythicine, (.+-.)-9-hydroxy-1,2,3,10-tetramethoxyaporphine, (.+-.)-dicentrine, and (.+-.)-thalicsimidine.

The skeleton of the title aporphines was synthesized by use of the lead tetraacetate oxidation of 1-(3-hydroxy-4-methoxybenzyl)-1, 2, 3, 4-tetrahydroisoquinolines.

The conversion of primary alcohols to the corresponding aldehydes by a modified lead tetraacetate oxidation

A novel metod for obtaining aldehydes in good yield from primary alcohols has been devised, using the combination lead tetraacetate—manganous diacetate as the oxidizing agent.

ChemInform Abstract: LEAD TETRAACETATE OXIDATION OF PHENYLHYDRAZONES OF 3‐BENZOYLAZOLES. SYNTHESIS OF AZOACETATES AND THEIR CONVERSION INTO INDAZOLES

AbstractAus den Hydrazonen (I) erhält man durch Bleitetraacetat‐Oxidation die Zwischenstufen (II), die mit AlCl3 als Lewissäure zu den Indazolen (III) führen.

Crystal and molecular structure of 3,4,4,5‐tetramethyl‐1‐(p‐methoxybenzoyl)‐5‐(p‐methoxybenzoylazo)‐2‐pyrazoline

AbstractThe crystal and molecular structure of the title compound, derived by lead tetraacetate oxidation of the bis‐p‐methoxybenzoylhydrazone of 3,3‐dimethylpentane‐2,4‐dione, is studied by an X‐ray crystallographic analysis.

Lead tetraacetate oxidation of phenylhydrazones of 3‐benzoylazoles. Synthesis of azoacetates and their conversion into indazoles

AbstractLead tetraacetate (LTA) oxidation of (E)‐ and (Z)‐phenylhydrazones of 3‐benzoyl‐5‐phenyl‐1,2,4‐oxadiazole, 3‐benzoyl‐5‐phenylisoxazole, and 3‐benzoyl‐4‐methyl‐1,2,5‐oxadiazole has been studied. Conversion of azoacetate products into 3‐(azol‐3‐yl)‐substituted indazoles has been achieved by reacting them with aluminium chloride in benzene at room temperature.

A Conventient Synthesis of 3-Hydroxy-4-chromanone Using Iodobenzene Diacetate

Abstract A useful synthesis of 3-hydroxy-4-chromanone (6) is not currently available. Lead tetraacetate oxidation of 4-chromanone (4) yields the C(3) acetoxy derivative but this compound could not be deacetylated to 6.1 Recently Donnelly and Maloney reported2 that the Algar-Flynn-Oyamada reaction (H2O2/CH3OH/NaOH), which is commonly used for the conversion of o-hydroxychalcones (1) into 3-hydroxyflavanone (2) and 3-hydroxyflavones (3), does not yield 6 when applied to o-hydroxya-crylophenone 1 (R = H). The authors found that under less basic conditions using K2CO3 some 6 is formed but the major product is catechol. These observations clearly indicate the necessity of developing a method for making 6. The present note describes a staightforward way of preparing 3-hydroxy-4-chromanone (6) in good yield.

Lead tetraacetate oxidation of oxyprotoberberines. A convenient synthesis of 13-oxygenated berbines and oxyprotoberberines

Synthese d'hydroxy-13 berbines (ophiocarpine et hydroxy-13β xylopinine) et d'acetoxy-13β deshydro-13 berbinones-8 par oxydation de deshydro-13 berbinones-8. Synthese de chilenine via l'hydroxy-13a dimethoxy-9,10 methylenedioxy-2,3 berbinedione-8,13

ChemInform Abstract: DESULFURIZATION OF N,N′‐DIARYLTHIOUREAS BY LEAD TETRAACETATE OXIDATION

AbstractDie Thioharnstoffe (I) werden von Pb‐tetraacetat desulfuriert, wobei elementarer Schwefel freigesetzt wird.