- TRANSITION METAL-PROMOTED REACTIONS. X. PENTACARBONYLIRON-PROMOTED REDUCTIVE COUPLING OF BENZOYL CHLORIDE IN HALOBENZENES
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Reductive coupling of benzoyl chloride to give trans- and cis-α,α'-stilbenediol dibenzoates is found to be promoted by pentacarbonyliron.The mechanism is briefly discussed.
- Luh, Tien-Yau,Lee, Kim Sze,Tam, S. W.
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- Methylsulfinyl (Dimsyl) anion as umpolung catalyst for the chemoselective cross-benzoin reaction of α-diketones with aldehydes
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The hitherto unreported ability of the methylsulfinyl carbanion (dimsyl anion) to generate acyl anion equivalents is described. The dimsyl anion, in fact, efficiently catalyzes chemoselective intermolecular cross-benzoin condensations of diaryl α-diketones (benzils) with various aromatic and aliphatic aldehydes to give the corresponding aryl-aryl and aryl-alkyl benzoin benzoates in an atom-economic fashion. The dimsyl anion acts as an environmentally friendly alternative to the toxic cyanide anion and it is obtained by in situ deprotonation of dimethyl sulfoxide (DMSO) solvent with a catalytic amount of a strong base, potassium tert-butoxide (t-BuOK) the optimal promoter. The assumption that the methylsulfinyl carbanion is the active catalyst in the title transformation is supported by electrospray ionization mass spectrometry (ESI-MS) experiments. Copyright
- Bortolini, Olga,Fantin, Giancarlo,Ferretti, Valeria,Fogagnolo, Marco,Giovannini, Pier Paolo,Massi, Alessandro,Pacifico, Salvatore,Ragno, Daniele
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p. 3244 - 3252
(2013/12/04)
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- Reactions of aroyl chlorides with samarium metal in DMF-controllable syntheses of O-aroylbenzoins, 1,2-diarylethanones, and (z)-α, α′-stilbenediol dibenzoates
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Reduction of aroyl chlorides carried out in DMF with samarium metal has been studied. Samarium metal, which requires not any intended activation or pretreatment, was found to react with aroyl chloride in a controllable manner. Correspondingly, O-aroylbenzoins, 1,2-diarylethanones, or (Z)-α, α′-stilbenediol dibenzoates were afforded as the major products under controlled conditions.
- Liu, Yongjun,Wang, Xiaoxia,Zhang, Yongmin
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p. 4009 - 4022
(2007/10/03)
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- Transformation of acid chlorides into aldehydes by reduction of in-situ formed acyltributylphosphonium ions with zinc-copper couple or zinc
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Transformation of acid chlorides into the corresponding aldehydes without over-reduction to alcohols was effectively achieved by the reduction of acyltributylphosphonium ions, formed in-situ from the chlorides and tributylphosphine in CH3CN, with Zn-Cu couple or Zn in the presence of CH3SO3H under an N2 atmosphere.
- Maeda, Hatsuo,Maki, Toshihide,Ohmori, Hidenobu
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p. 2247 - 2250
(2007/10/02)
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- Cathodic reduction of enediol diesters obtained by electrochemical methods
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The electrochemical reduction of 1,2-di-alkylphenyl-1,2-ethenediol di- alkylbenzoates, on a Hg cathode in DMF/LiClO4, yields 1,2-di- alkylphenylacetylenes. The enediol diesters were obtained from alkylbenzoyl chlorides, by the same method, using dry acetone / LiClO4.
- Polo,Quintanilla,Barba
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p. 907 - 915
(2007/10/02)
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- Neue Synthesen und Reaktionen ungesaettigter Heterotitanacyclen
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Dicarbonyltitanocene reacts chemoselectively with difunctional carbonyl compounds such as 1,2-diketones and 1,4-diketo-2-enes, with α-ketothioketones, α-ketoimines and azodicarbonic esters and -amides to yield the corresponding, mostly new, heterotitanacycles that are capable of a lot of a useful follow-up reactions.These chelate complexes, containing three to four heteroatoms, allow the substitution of the entire titanocene fragment by carbon (formation of vinylenic carbonates and the thia-derivatives of these) or by further heteroatoms like boron or phosphorus(formation of boroles and phosphonic acid derivatives), thus retaining the cyclofunctionality.Alternatively, some of the new chelate complexes can be readily C-C-chain-lengthened via a deprotonating/alkylating sequence, leaving the metallacycle unaffected.
- Duerr, Stefan,Hoehlein, Udo,Schobert, Rainer
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- Synthesis, Thermal Stability, and Chemiluminescence Properties of Bisdioxetanes Derived from p-Dioxines
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By elimination of methanol from 2,5-dimethoxy-1,4-dioxanes and 2,3-dihydro-2-methoxy-1,4-dioxines on treatment with p-toluenesulfonic acid in acetic anhydride, the new tetrakis(4-methoxyphenyl)-, tetrakis(4-chlorophenyl)-, tetra-p-tolyl-, and 2,5-dimethyl-3,6-diphenyl-1,4-dioxines (1) were prepared in good yields.Photosensitized singlet oxygenation of these 1,4-dioxines 1 afforded the corresponding bisdioxetanes 2, the 1,2-diketones, and the enediol diesters 7.Thermal decomposition of the bisdioxetanes 2 yielded the corresponding anhydrides 4 essentially quantitatively.During the thermolysis of 1,6-dimethyl-3,8-diphenyl-2,4,5,7,9,10-hexaoxatricyclo3,6>decane (2f) appreciable amounts of (3R,4S)-3-acetoxy-4-(benzoyloxy)-4-methyl-3-phenyl-1,2-dioxetane (3f) were detected.The bisdioxetanes 2 and monodioxetane 3f exhibited similar thermal stabilities, the free energies of activation (ΔG%) at 298 K falling within 25.5 + 1.5 kcal/mol.The singlet excitation yields (ΦS) ranged between 0.003 and 0.03percent and the triplet excitation yields (ΦT) between 9.5 and 71.5percent.Despite the favorable energy balance, it is concluded that no higher excited states of anhydride 4f are produced during the thermolysis of bisdioxetane 2f.On thermal activation, the bisdioxetanes decompose by sequential cleavage of the two dioxetane rings.
- Adam, Waldemar,Platsch, Herbert,Schmidt, Ernst
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p. 4385 - 4403
(2007/10/02)
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- SYNTHESIS OF (Z)-STILBENDIOL DIBENZOATE BY SENSITIZED PHOTOOXYGENATION OF 2,3,5,6-TETRAPHENYL-p-DIOXIN
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Sensitized photooxygenation of 2,3,5,6-tetraphenyl-p-dioxin with singlet and triplet excitable sensitizers yields (Z)-stilbendiol dibenzoate together with benzil.Experimental proofs show that unconnected mechanisms could operate accounting for the 1,2-diketone and the endiol diester formation.
- Lopez, Luigi
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p. 4383 - 4386
(2007/10/02)
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- FACILE HIGH YIELD SYNTHESIS OF ENEDIOL DIESTERS
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Cathodic reductions of diaryl-1,2-diketones are carried out in the presence of acylating reagents.The respective enediol diesters are obtained in high yields.The products are formed by reaction of electrogenerated intermediates with the acylating agents.
- Guirado, A.,Barba, F.,Tevar, A.
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p. 333 - 338
(2007/10/02)
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- Studies on the Occurence of Hydrogen Transfer, 67. Enediol Diesters by Acylating Electroreductive Dimerization of Acyl Chlorides with Lithium Amalgam
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Aromatic, aliphatic, and aromatic-aliphatic acyl chlorides (and anhydrides) are transformed by lithium amalgam (Li/Hg) to cis- and/or trans enediol diesters 1-10 (acylating reductive dimerization), mostly in ca. 70percent yields.The influence of the solvent on the reaction course is investigated.Starting from 2,2'-biphenyldicarbonyl dichloride, the phenanthrene 7 is formed; phthalide 8 is the reaction-product using phthaloyl dichloride as starting material.Diphenylphosphinyl chloride is reduced by Li/Hg to tetraphenyldiphosphane dioxide (15).A reaction mechanism for the acylating reductive dimerization is proposed on the basis of the halve-wave potentials determined for 12 acyl chlorides and four 1,2-diketones.The latter are intermediates in the acylating reductive dimerization of the acyl chlorides.Enediol diesters are obtained starting from 1,2-diketones and Li/Hg in the presence of acyl chlorides.Trimethylsilyl chloride is unsuitable as a trap for the enediols; it is preferentially reduced at the Li/Hg interface.Tetrahydrofuran as solvent is transformed to RC(O)O-4-Cl by a known ring-opening acylation reaction in the presence of Lewis acids (LiCl or ZnCl2) formed by the decomposition of Li/Hg and Zn/Hg.
- Horner, Leopold,Dickerhof, Karlheinz
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p. 1603 - 1614
(2007/10/02)
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- Reaction of Organic Tin(II) Compounds with Carbonyl Compound
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The reactions of organic tin(II) compounds bearing Sn-OC bonds with carbonyl compounds, C6H5COR (R = C6H5CO, C6H5, and H) and p-benzoquinone, have been investigated.The tin(II) compound reacted with benzil and p-benzoquinone to yield the corresponding oxi
- Wakeshima, Ikuko,Kijima, Ichiro
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p. 2345 - 2347
(2007/10/02)
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