2819-08-1Relevant articles and documents
Green and Efficient: Iron-Catalyzed Selective Oxidation of Olefins to Carbonyls with O2
Gonzalez-De-Castro, Angela,Xiao, Jianliang
supporting information, p. 8206 - 8218 (2015/07/15)
A mild and operationally simple iron-catalyzed protocol for the selective aerobic oxidation of aromatic olefins to carbonyl compounds is described. Catalyzed by a Fe(III) species bearing a pyridine bisimidazoline ligand at 1 atm of O2, α- and β-substituted styrenes were cleaved to afford benzaldehydes and aromatic ketones generally in high yields with excellent chemoselectivity and very good functional group tolerance, including those containing radical-sensitive groups. With α-halo-substituted styrenes, the oxidation took place with concomitant halide migration to afford α-halo acetophenones. Various observations have been made, pointing to a mechanism in which both molecular oxygen and the olefinic substrate coordinate to the iron center, leading to the formation of a dioxetane intermediate, which collapses to give the carbonyl product. (Chemical Equation).
Development of a mild and efficient protocol for the protection and O-alkylation of allyl alcohols
Selvakumar, Kodirajan,Prasath Lingam, Kandapalam Arun,Luxmi Varma, Rama Varma
, p. 36538 - 36543 (2014/11/07)
An efficient, pyridine-free protocol has been developed for the protection of the 3°-allyl alcohol of oxindole using a mild base, such as potassium carbonate, under microwave irradiation conditions. The methodology has been tested with a variety of substrates and protecting group reagents, which provides a clean and good yield of the desired products within a short reaction time. the Partner Organisations 2014.
Molecular iodine in isopropenyl acetate (IPA): a highly efficient catalyst for the acetylation of alcohols, amines and phenols under solvent free conditions
Ahmed, Naseem,van Lier, Johan E.
, p. 5345 - 5349 (2007/10/03)
Iodine in isopropenyl acetate (IPA) is a highly efficient catalyst for the acetylation of a variety of alcohols, phenols and amines under solvent free conditions. Primary, secondary, tertiary alcohols, amines and mono to polyhydroxy phenols and anilines with electron donating or withdrawing substituents can be easily acetylated in good to excellent yield at 85-90 °C.
Synthesis of anhydrides from acyl halides and zinc carboxylates under aprotic conditions
Pasha,Rizwana
, p. 420 - 421 (2007/10/03)
Synthesis of symmetric as well as unsymmetrical carboxylic acid anhydrides from zinc carboxylates and acid chlorides under aprotic conditions in high yields is reported.
A facile synthesis of acid anhydrides
Dubey,Kumar, R. Vinod
, p. 1 - 3 (2007/10/03)
A facile synthesis of symmetric and unsymmetric acid anhydrides using phase-transfer catalysis is described. By this method different types of anhydrides can be obtained in high yields under mild conditions even on microscale levels.
Quinolone carboxylic acid derivatives and process for preparing the same
-
, (2008/06/13)
The present invention relates to novel quinolone carboxylic acid derivatives having useful antibacterial activities of formula (I): STR1 wherein, R1, R2, and R3, which may be the same or different, are each hydrogen or a h
Modification of the photochemical reactivity of α,β-diacetoxystilbene by adsorption onto a Fe3+-doped sepiolite: Comparison with the direct and 2,4,6-triphenylpyrylium-sensitized photolyses
Baldovi,Garcia,Miranda,Primo,Soto,Vargas
, p. 8113 - 8120 (2007/10/02)
Photolysis of α,β-diacetoxystilbene (1) adsorbed onto a Fe3+-doped sepiolite (Fe-Sp) leads to benzoic acid (3), 9,10-diacetoxyphenanthrene (5), diphenic anhydride (6), and benzil (7). While compounds 3, 5 and 6 are also observed in the direct irradiation of 1 in hexane solution, diketone 7 is formed under electron transfer conditions using 2,4,6-triphenylpyrylium tetrafluoroborate as photosensitizer. These results strongly suggest that formation of benzil (7) in the photolysis of 1 on Fe-Sp involves the intermediacy of 1+·, generated by single electron transfer from excited 1 to the iron active sites of the clay. In contrast to the unsubstituted stilbene, reactivity of 1+· with ground state molecular oxygen has been established by cyclic voltammetry through the current intensity decrease of the oxidation peak of 1 in the presence of oxygen. Finally, the thermodynamic feasibility of a direct electron transfer pathway between excited 1* and oxygen leading to the formation of a dioxetane intermediate is discussed.
Novel quinolone carboxylic acid derivatives and process for preparing the same
-
, (2008/06/13)
The present invention relates to novel quinolone carboxylic acid derivatives of formula (I): wherein,R1, R2 and R3,which may be the same or different, are each hydrogen or a halogen atom, or a lower alkyl group or a lower
Synthesis and Thermolysis of Ketal Derivatives of 3-Hydroxy-1,2-dioxolanes
Baumstark, A. L.,Vasquez, P. C.,Chen, Y.-X.
, p. 6692 - 6696 (2007/10/02)
3--3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (2), 3-methoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (3), and 3-acetoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (4) were synthesized from the corresponding 3-hydroxy-1,2-dioxolane (1a) under basic conditions. 3-Acetoxy-4,4-dimethyl-3,5,5-triphenyl-1,2-dioxolane (5) was also synthesized via this approach.Under acidic conditions, 3-hydroxy-1,2-dioxolane 1a underwent quantitative decomposition to phenol and 3,3-dimethyl-2,4-pentanedione.This competing degradation was dependent on the nature of the substituents at position-5.Methyl groups at position-5 slowed the degradative rearrangement whereas phenyl groups favored it. 3-Methoxy- and 3-(allyloxy)-4,4,5,5-tetramethyl-3-phenyl-1,2-dioxolanes (6, 7) were synthesized under acidic conditions from the appropriate 1,2-dioxolane precursors and the corresponding alcohols.At 60 deg C, derivatized 1,2-dioxolanes 2-7 were found to be more stable than the corresponding 3-hydroxy-1,2-dioxolanes.The first order rate constants for the thermolysis of 1,2-dioxolanes 2-7 were determined.Product studies showed that thermolysis of 2-5 yielded pairs of ketones and derivatized carboxylic acids.In addition to R-group migration products, an acetoxy migration product was observed for the thermolysis of 4.Thermolysis of 6 at 60 deg C in benzene yielded methyl benzoate and pinacolone, quantitatively.Thermolysis of 7 yielded products analogous to those for 6.No evidence for internal trapping of radicals by the carbon-carbon double bond of the allyloxy group in 7 was found.The thermolysis appeared to proceed with peroxy bond homolysis as the rate-determining step.Subsequent β-scissions of the intermediate 1,5-oxygen diradical with interesting rearrangements that show a high preference for alkyl vs phenyl migration account for the observed product distributions.The results suggest that the β-scission/rearrangement mechanism may not be concerted but rather stepwise to yield 1,3-diradical and carbonyl fragments.