Barton studies

Sufficient evidence is available to indicate that atmospheric pollution in vaiying degrees does affect health adversely. [Amdur, Melvin, and Drinker, Effec t of Inhalation of Sulfur Dioxide by Man, Lancet, 2, 758 (1953) Barton, Corn, Gee, VassaUo, and Thomas, Response of Healthy Men to Inhaled Low Concentrations of Gas-Aerosol Mixtures, Arch. Lnviron. Health, 18, 681 (1969) Bates, Bell, Burnham, Hazucha, and Mantha, Problems in Studies of Human Exposure to Air Pollutants, Can. Med. A.s.soc. J., 103, 833 (1970) Ciocco and... 

Reduction of a conjugated enone to a saturated ketone requires the addition of two electrons and two protons. As in the case of the Birch reduction of aromatic compounds, the exact order of these additions has been the subject of study and speculation. Barton proposed that two electrons add initially giving a dicarbanion of the structure (49) which then is protonated rapidly at the / -position by ammonia, forming the enolate salt (50) of the saturated ketone. Stork later suggested that the radical-anion (51), a one electron... 

The reaction of Grignard reagents with the keto group of 5a-cholestan-3-one (7) was first described in 1937/ In a later study, Barton obtained the two epimeric tertiary alcohols (8) and (9), in a ratio of 40 60 by exposing (7) to the action of methyl Grignard reagent. 

In more recent studies, the Barton group has shown that 0-acyl thiohydroxamates (thiohydroxamate esters) are convenient sources of alkyl radicals.490,51,52 Barton s thiohydroxamate ester chemistry is mild and easily executed, and the intermediate organic radicals are amenable to a wide variety of useful transformations. A thiohydroxamate ester of the type 125 (see Scheme 23) can be formed... 

Barton, J. M. The Application of Differential Scanning Calorimetry (DSC) to the Study of Epoxy Resins Curing Reactions. Vol. 72, pp. 111 — 154. 

Barton and coworkers have shown that proteins can in fact modulate the DNA electron transfer [168]. Methyltransferases are enzymes that recognize distinct DNA sequences, e.g., 5 -G CGC-3, and effect methylation by extrading the target base cytosine ( C) completely out of the DNA duplex while the remainder of the double helix is left intact. The methyltransferase Hha 1-DNA complex is a well-characterized example, revealing that the structure of the DNA is significantly but locally distorted [169,170]. In a recent study, Raj ski et al. used DNA duplex 20 containing the M.Hha I binding site between two oxidizable 5 -GG-3 sites [168] (Fig. 20). The duplex contains a complementary strand, selectively 5 -modified with a Rh intercalator that can function as a photooxidant. Upon... 

The value of the activity coefficients of FeS in sphalerite determined for temperatures above 300°C can be extrapolated to lower temperatures. As stated by Barton and Toulmin (1966), ypeS does not depend on temperature above about 270°C. However, the activity coefficient below 270°C has not been studied. Scott and Kissin (1973) have stated that activity coefficients for FeS in sphalerite at low temperatures may be substantially different from those at higher temperatures. 

St Armand, Barton Levi. Poe s "Sober Mystification" the uses of alchemy in "The Gold Bug". Poe Studies 4, no. 1 (Jun 1971) 1-7. rhttp //www.eapoe.org/pstudies/psl970/pl971101.html. 

Barton has reported a wide variety of elegant studies in which various silenes or silylenes have been created, usually thermally, and their subsequent rearrangements investigated in terms of the observed products of trapping (51,53,65,145). It has been clearly established that interconversion between silenes and silylenes, especially where H atoms or Me3Si groups migrate, are facile processes. In some cases, radicals can be the precursors to silenes (65). 

Charache S, Terrin ML, Moore RD, Dover GJ, Barton FB, Eckert SV, McMahon RP, Bonds DR. Effect of hydroxyurea on the frequency of painful crises in sickle cell anemia. Investigators of the Multicenter Study of Hydroxyurea in Sickle Cell Anemia [see comments). 

Another type of ring opening has been demonstrated by Barton et al.Sb in their study of the photochemistry of 2-phenylselenophene. Upon irradiation, 2-phenylselenophene (68) gives a mixture of 3-phenylselenophene (70), phenylvinylacetylene (69), and selenium (Eq. 25). 

Gammon R., Roy A., Barton J., Little M., Case Study—Hydrogen and Renewables Integration (HARI), lEA-Hydrogen Implementing Agreement, 2006. 

Jastrzebski Z, Leontowicz H, Leontowicz M, Namiesnik J, Zachwieja Z, Barton H, Pawelzik E, Arancibia-Avila P, Toledo F and Gorinstein S. 2007. The bioactivity of processed garlic (Allium sativum L.) as shown in in vitro and in vivo studies on rats. Food Chem Toxicol 45(9) 1626—1633. 

L.S. Swanson, J. Shinar, Y.W. Ding, and T.J. Barton, Photoluminescence, electroluminescence, and optically detected magnetic resonance study of 2,5-dialkoxy derivatives of poly(p-phenylene acetylene) (PPA) and PPA-based light-emitting diodes, Synth. Met., 55 1-6, 1993. 

The first direct evidence for the structure of platinum-blues was provided by the single-crystal X-ray studies of cis-diammineplatinum a-pyridonate-blue, [Pt(2.25+)4(NH3)8(/x-a-pyridonato-N,0)4] (N03)5 H20 (48, 49). In the study, Barton and Lippard selected a-pyridone as a simplified model of pyrimidine bases (see Fig. 3), which must be the primary reason of their success in obtaining the first crystalline-blue material. 

Only a few more recent examples of the numerous studies on N-arylations with aryllead triacetates will be discussed here. For earlier publications in this field, the interested reader is referred to the pioneering arylations of aliphatic and aromatic amines by Barton s group, 8 as well as the comprehensive review article by Elliott and... 

The allyl alcohol trapping reaction was further studied by Crich and coworkers, who applied the Barton decarboxylation reaction as radical source,... 

The l-oxa-2,4,5-cycloheptatrienes 602 and 603 were postulated to be intermediates in the rearrangement of certain (ethynylfuryl)oxiranes to furo[3,4-b]furans [251]. The replacement of the methylene groups of 1,2-cycloheptadiene (465) by SiMe2 groups and the introduction of substituents at the allene moiety allowed the preparation of isolable seven-membered ring allenes. Thus, Barton et ah [177] obtained 604 and Ando et al. [178] 605. A few reactions of these systems have also been studied [177, 252]. Both groups [178, 253] synthesized the [4.4]betweenallene 606 and determined its structure by X-ray diffraction. 

Barton, D. H. R. Crich, D. Motherwell, W. B. J. Chem. Soc., Chem. Commun. 1983, 939. Derek Barton (United Kingdom, 1918—1998) studied under Ian Heilbron at Imperial College in his youth. He taught in England, France and the US. Barton won the Nobel Prize in Chemistry in 1969 for development of the concept of conformation. He passed away in his office at the University of Texas at Austin. 

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