- FACILE OXIDATIVE CYCLIZATION AND CARBONYLATION OF ALLYLIC ALCOHOLS
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Palladium chloride catalyzed reaction of primary, secondary, and tertiary allylic alcohols with carbon monoxide and oxygen, hydrochloric acid, and cupric chloride in tetrahydrofuran affords five-membered ring lactones.
- Alper, Howard,Leonard, Daniele
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- On the mode of baker's yeast reduction of C-7 - C-10 2-alken-4-olides
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Baker's yeast reduction of lactones 8, a-d proceeds under kinetic resolution to give (S) 11, a-d of low ee values, increasing with the length of the side chain, occurring the double bond saturation in anti fashion on the beta re face, as indicated by the obtainment from 4 and 6 of 5 and 7, respectively.
- Fronza, Giovanni,Fuganti, Claudio,Grasselli, Piero,Mele, Andrea,Sarra, Antonella,Allegrone, Gianna,Barbeni, Massimo
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- Organocatalytic stereoselective approach to the total synthesis of (-)-halosaline
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A practical and efficient organocatalytic approach to the synthesis of substituted piperidine alkaloids in high enantio- and diastereomeric excess was achieved using proline-catalyzed sequential α-aminoxylation/α- amination reaction and HWE olefination reaction of an aldehyde.
- Jha, Vishwajeet,Kumar, Pradeep
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p. 3238 - 3244
(2014/01/06)
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- A new synthesis of γ-butyrolactones via AuCl3- or Hg(II)-catalyzed intramolecular hydroalkoxylation of 4-bromo-3-yn-1-ols
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An efficient conversion of 4-bromo-3-yn-1-ols to γ-butyrolactones via AuCl3-catalyzed electrophilic cyclization (hydroxyl-assisted regioselective hydration) in wet toluene is described. Various secondary and tertiary alcohols including benzylic systems were found to be equally reactive with moderate to excellent yields obtained in all cases.
- Reddy, Maddi Sridhar,Kumar, Yalla Kiran,Thirupathi, Nuligonda
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supporting information; experimental part
p. 824 - 827
(2012/04/05)
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- Reactions of hydriodic acid with aldonolactones and n-alkanolactones. Interconversions between lactones and iodocarboxylic acids
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Aldonolactones containing from four to eight carbon atoms, and lactones of the related monohydroxy-n-alkanoic acids, were subjected to reaction with 57 percent hydriodic acid at 125 deg C.As in the classical studies of Kiliani, the reduction of D-glycero-D-ido-heptono-1,4-lactone yielded mainly γ-heptanolactone.Analogously, the corresponding γ-alkanolactones were obtained as major products from the 1,4-lactones of the D-xylono, D-allono-, and D-erythro-L-talo-octono configuration.Monoiodo-n-alkanoic acids were also formed in admixture with the lactones in all of these reactions.D-Erythrono-1,4-lactone was unique among the aldonolactones in that it led only to an acid, i.e., 3-iodo-n-butanoic acid.The latter was also the product of the non-reductive reaction of hydriodic acid with β-butyrolactone whereas, by contrast, γ-butyrolactone afforded 4-iodobutanoic acid.Among compounds in the five to eight carbon series, it was found that under conditions close to equilibrium the ratio of lactone to iodoacid decreased progressively with the length of the carbon chain; e.g., in the 4 h reactions of γ-valero, γ-capro, γ-heptano,- and γ-octanolactone, the ratios were 2.4, 1.2, 0.2, and 0.1, respectively.An accompanying characteristic of these reactions is a progression in the number of isomeric iodoacids formed.Whereas γ-valerolactone was accompanied by 4-iodopentanoic acid, there were two isomers (4- and 5-) of iodohexanoic acid, three monoiodo- (including 6-iodo-) heptanoic acids, and four (including 7-iodo-) octanoic acids.In all instances, the isomer substituted at the penultimate carbon was major.An interplay of several individual reactions, including ring-opening displacements, eliminations-additions, and rearrangements, as well as a probable influence of entropy changes on the lactone-acid equilibria, appear to account largely for these observations.
- Liu, Zhengchun,Granata, Alessandro,Shen, Xinhua,Perlin, Arthur S.
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p. 2081 - 2088
(2007/10/02)
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- Lactonization of Unsaturated Alcohols Catalyzed by Palladium Complexes under Neutral Conditions
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Secondary and tertiary allylic alcohols react with carbon monoxide in the presence of catalytic quantities of bis(dibenzylideneacetone)palladium (0) and 1,4-bis(diphenylphosphino)butane affording lactones in 45-92percent isolated yields. α,β-Unsaturated acids are formed by isomerization and carbonylation of primary allylic alcohols. 2-(5H)-Furanones were isolated in yields of 60-80percent when alkynols were employed as substrates for the cyclocarbonylation process.
- El Ali, Bassam,Alper, Howard
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p. 5357 - 5360
(2007/10/02)
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- 3,3-Diethoxypropyl-lithium: A Masked Lithium Propanal Homoenolate in Organic Synthesis
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3,3-Diethoxypropyl-lithium is prepared by lithiation of the corresponding chlorinated precursor with lithium naphthalenide at -78 deg C; the reaction of this masked propanal homoenolate with different elctrophilic reagents CO, (CH2)7CO, PhCOMe, PhCH=NPh, PhCONEt2, PhCN, c-C6H11CN, 4-MeC6H4CN> leads to the corresponding mono- and bi-functionalized compounds.In the case of the reaction with aldehydes or ketones the prepared crude products are oxidized with m-chloroperbenzoic acid, yielding directly the γ-substituted butyrolactones.
- Barluenga, Jose,Fernandez, Jose R.,Rubiera, Covadonga,Yus, Miguel
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p. 3113 - 3118
(2007/10/02)
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- Samarium(II) Di-iodide Induced Reductive Coupling of α,β-Unsaturated Esters with Carbonyl Compounds Leading to a Facile Synthesis of γ-Lactone
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Samarium(II) di-iodide, which is a strong one-electron transfer reducing agent, is effective for the reductive coupling of α,β-unsaturated esters with carbonyl compounds, whereby substituted γ-lactones can easily be prepared in good to excellent yields under very mild conditions.Two mole equiv. of samarium(II) di-iodide to each mole equiv. of starting substrate always give reasonable yields.The presence of an alcohol is essential in the reaction, complex unidentified products being formed in the absence of an alcohol; t-butyl alcohol gave more satisfactory results than methanol and ethanol.The alcohol acts as a proton donor, the use of MeOD leading to a deuteriated γ-lactone.The reaction is applicable to both aliphatic and aromatic ketones or aldehydes, whereas the electrochemical method is limited to aliphatic substrates.The diastereoselectivity is examined in the reaction of 4-t-butylcyclo-hexanone with ethyl acrylate; an anti-isomer is produced predominantly (syn:anti = 1:9) as the result of selective axial attack.The reaction may proceed by a radical mechanism, and reaction may not involve a samarium ester homoenolate.The reaction is extended to the intramolecular reaction of an α,β-unsaturated keto ester (8-oxonon-2-enoate) leading to the ready synthesis of a bicyclic γ-lactone.
- Fukuzawa, Shin-ichi,Nakanishi, Akira,Fujinami, Tatsuo,Sakai, Shizuyoshi
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p. 1669 - 1676
(2007/10/02)
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- Reductive Coupling of Ketones or Aldehydes with Electron-deficient Alkenes Promoted by Samarium Di-iodide
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Samarium di-iodide is an efficient reagent for the reductive coupling of ketones or aldehydes and electron-deficient alkenes, whereby γ-lactones can be prepared in good yields from ethyl acrylate.
- Fukuzawa, Shin-ichi,Nakanishi, Akira,Fujinami, Tatsuo,Sakai, Shizuyoshi
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p. 624 - 625
(2007/10/02)
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- Oxonium Ion Elektrophiles: Synthesis of the Hypotensive Oudenone.
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The hypotensive oudenone (1) has been synthesized through the intermediacy of oxonium ion 4.Acid-catalyzed C-alkylation of 1,3-cyclopentanedione (3) with 5-propyltetrahydro-2-furanol (6b) afforded dihydrooudenone 2b.In contrast, alkylation of 3 with 2-chloro-5-propyltetrahydrofuran (7b) was unsuccessful.Unsaturation was introduced into 2b by treatment with N-(phenylthio)succinimide to produce 10 followed by oxidation to the corresponding sulfoxide and elimination of phenylsulfenic acid, which produced oudenone(1).
- Bates, Hans, Aaron,Farina, James
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p. 3843 - 3845
(2007/10/02)
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- Electroorganic Chemistry. Part 73. Electroreductive Cross-coupling of 3-Substituted Alkanoic Acid Esters with Aldehydes or Acid Anhydrides
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Elecroreductive cross-coupling reaction of 3-phenylthioalkanoic acids esters (4a) or quaternary ammonium salts of 3-aminoalkanoic acid esters (4b) with aldehydes gave the corresponding γ-lactones in one step.The cross-coupling reaction of (4b) with acid anhydrides leading to the formation of the corresponding γ-keto esters is also described.
- Shono, Tatsuya,Matsumura, Yoshihiro,Kashimura, Shigenori
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p. 1922 - 1935
(2007/10/02)
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- Direct Oxidation of Alkanoic Acids and their Amides to γ-Lactones by Peroxydisulphate-containing Systems
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The reaction of one-electron oxidation of alkanoic acids (I) and their amides (VI) on treatment with Na2S2O8-containing systems has been studied.As a result of the direct one-pot reaction acids (I) and amides (VI) are converted into γ and δ-lactones, the reaction being regioselective and leading mainly to γ-lactones in up to 35percent yield.The regioselectivity of the oxidative lactonisation depends greatly on the nature of alkyl substituents.The results obtained are presented in terms of a mechanism suggesting the generation of acyloxyl and amidyl radicals from (I) and (VI), respectively, followed by a rearrangement via a 1,5- or 1,6-H shift into the corresponding 3- and 4-carboxy- or -carboxamido-alkyl ra The latter undergo oxidative cyclisation to produce γ and δ lactones.The system Na2S2O8-NaCl-NaOH converts carboxamides (VI) into amines with loss of one carbon atom as a result of a Hoffmann type rearrangement.
- Nikishin, Gennady I.,Svitanko, Igor V.,Troyansky, Emmanuil I.
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p. 595 - 602
(2007/10/02)
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- Electroreductive hydrocoupling of activated olefins with ketones or aldehydes in the presence of trimethylchlorosilane
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Electroreductive crossed hydrocoupling of α,β-unsaturated esters with aldehydes or ketones in the presence of trimethylchlorosilane afforded γ-lactones in good yields. Similarly, α,β-unsaturated nitriles gave γ-hydroxynitriles in high yields.
- Shono, Tatsuya,Ohmizu, Hiroshi,Kawakami, Souta,Sugiyama, Hiroshi
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p. 5029 - 5032
(2007/10/02)
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