Kochi studies

Kochi studied the selective excitation of preformed ground-state charge transfer complexes [85]. Irradiation of the long wavelength band of these species results... 

Tamura and Kochi studied the cross-coupling reactions of alkyl halides with alkyl Grignard reagents catalyzed by silver compounds first [422, 426, 427]. The coupling of primary alkyl halides with primary Grignard reagents resulted in a mixture... 

More recently, Kochi studied the decarboxylation of acyloxyl radicals generated by PET in charge transfer ion pairs between benzilate anions (Ar2C(0H)C02 ) and a cationic acceptor (methylviologen di-cation (MV +) or A-methyl-4-cyano-pyridinium (NCP+)) in aqueous solution (Scheme 70) [232, 233]. 

Note, Added in Proof-. In their study of the autoxidation of 2-butyl-isoindoline, Kochi and Singleton showed that 2-butylisoindole is formed and is converted by further oxidation to 2-butylphthalimide and 2-butylphthalimidine. The rate of oxidation of 2-butylisoindoline to the isoindole was found to be markedly dependent on hydrogen donor ability of the solvent and was shoivn to involve a free radical chain process. Autoxidation of 2-butylisoindole also appears to be a radical process since it can initiate autoxidation of 2-butylisoindoline. 

Kochi (1956a, 1956b) and Dickerman et al. (1958, 1959) studied the kinetics of the Meerwein reaction of arenediazonium salts with acrylonitrile, styrene, and other alkenes, based on initial studies on the Sandmeyer reaction. The reactions were found to be first-order in diazonium ion and in cuprous ion. The relative rates of the addition to four alkenes (acrylonitrile, styrene, methyl acrylate, and methyl methacrylate) vary by a factor of only 1.55 (Dickerman et al., 1959). This result indicates that the aryl radical has a low selectivity. The kinetic data are consistent with the mechanism of Schemes 10-52 to 10-56, 10-58 and 10-59. This mechanism was strongly corroborated by Galli s work on the Sandmeyer reaction more than twenty years later (1981-89). 

D. J. Edge and J. K. Kochi, Effects of halogen substitution on alkyl radicals conformational studies by electron spin resonance. J. Am. Chem. Soc. 94(18), 6485-6495 (1972). 

Complementary to the work with aqueous acidic media is the study of the homolytic decompositions of Co(III) carboxylates in carboxylic acid media by Lande and Kochi . For example, Co(III) is reduced in pivalic acid media with first-order kinetics with E = 30.6 kcal.mole , AS = 8 eu and k ko = 1.28+0.10 (69 °C). The main oxidation products were found to be isobutylene and tert-butyl pivalate, which suggests that (CH3)3C- is an intermediate. Oxidative decarboxylation is the probable course in the analogous oxidations of n-butyric and isobutyric acids, in view of the production of propane and CO2 under normal... 

Relating the effects caused by specific allelochemicals to those caused by an allelopathic plant is complicated because the inhibitory substances released from a plant are often unknown, and generally several different compounds are involved. However, the actions of the weeds studied in our investigations have certain parallels to those found from pCA and FA. The allelopathic nature of Kochi a, Jerusalem artichoke, and cocklebur was established, since both aque-ous extracts and weed residues reduced sorghum growth. The data show a concentration dependency characteristic of allelopathy, and some difference in toxicity among the three weeds was observed with cockle-bur the most toxic. 

Tona, M., Study on Spherical Microlasers Levitated in an Ion Trap, Kochi University of Technology, Kochi, 2002... 

The formation of the monocationic intermediate (ArH)2Fe+ attendant upon the charge-transfer excitation of either the ferrocene or methylan-thracene EDA complex (7a and 7b) is responsible for the photo-induced de-ligation of bis(arene)iron(II), as described in (6). Thus, transient electrochemical studies (Karpinski and Kochi, 1992a,b) show that the catalytic de-ligation of (ArH)2Fe+ proceeds rapidly via a (two-step) electron-transfer chain or ETC process (8). 

The initial question was whether the active catalyst is copper metal, copper(I), or copper(II), because all metal precursors gave results. Without the proper control of the valence state and the ligand environment the selectivities for the copper catalysed cyclopropanations (or carbene insertion reactions) have remained low or inconsistent for a long period of time. It was only in the sixties that a more systematic study of these issues was started. Several divalent copper salts were successfully used, but Kochi and Salomon [1] showed with the use of Cu(I)OTf that most likely copper(I) was the actual species needed for this reaction. 

Kochi and co-workers studied photoinduced Diels-Alder cycloadditions via direct photoexcitation of anthracene as a diene with maleic anhydride and various maleimides as dienophiles. Here, fluorescence-quenching experiments, time-resolved absorption measurements, and the effect of solvent polarity provide striking evidence for an ion-radical pair to be the decisive intermediate [83],... 

In 1951 Roberts and Mazur observed that the free radical chlorination of methylcyclopropane gave a mixture of cyclopropylmethyl chloride and 4-chloro-l-butene (equation 74). This reaction was studied furtherand in 1969 Kochi, Krusic, and Eaton observed the cyclopropylmethyl radical 46 by ESR and also monitored its rearrangement. 

It should be seen that Equation 23.37 allows a pathway for the reduction of the reactant, (CO)2Mn(r]2-dppe)2+, separate from that of the heterogeneous pathway of Equation 23.34. Quantification of the extent to which the homogeneous cross-reaction contributes to the redox process almost always requires digital simulations that attempt to fit the shape of the whole CV curve. Such studies allowed Kuchynka and Kochi (25), for example, to obtain values for the rate constants of Equation 23.37 (kf = 200 M 1 s 1, kb = 20 s 1), and to... 

The acidolysis of the ion (XIV) was studied by Kochi and Buchanan53, using aqueous ethanol as solvent and buffers such as acetic acid-acetate. They postulated a two-step process in which (XIV) first undergoes a reversible nucleophilic substitution by some nucleophilic species X, and the resulting intermediate then is subject to a rate-determining acidolysis. Kochi and Buchanan53 wrote these steps as... 

Reid DL, Armstrong DA, Rauk A, Nese C, Schuchmann MN, Westhoff U, von Sonntag C (2003) H-atom abstraction by C-centered radicals from cyclic and acyclic dipeptides. A theoretical and experimental study of reaction rates. Phys Chem Chem Phys 5 3278-3288 Roberts BP (1996) Understanding the rates of hydrogen abstraction reactions empirical, semi-em-pirical and ab initio approaches. J Chem Soc Perkin Trans 2 2719-2725 Russell GA (1973) Reactivity, selectivity, and polar effects in hydrogen atom transfer reactions. In Kochi JK (ed) Free radicals. Wiley, New York, pp 275-331 Russo-Caia C, Steenken S (2002) Photo- and radiation-chemical production of radical cations of methylbenzenes and benzyl alcohols and their reactivity in aqueous solution. Phys Chem Chem Phys 4 1478-1485... 

The mechanism of mercuration is shown in Scheme 2. In the first step, the mercury salt forms a Jt-complex with the aromatic substrate [15, 16]. In 1982, Lau, Huffman, and Kochi [17] reported the first isolation and full characterization (including X-ray molecular and crystal structure) of such an intermediate, a complex of hexamethylbenzene with Hg(TFA)2. The X-ray structure revealed a Hg2( -TFA)i framework with a molecule of C6Me6 -coordinated to each of the Hg atoms. Analogous Jt-complexes have also been observed and studied by Dean and co-workers [18] and more recently by Barron s [19] and Gabbai s [20] groups. The Jt-complex intermediate can rearrange to the ej-complcx (a Wheland intermediate) directly, or sometimes via electron transfer, to produce a radical ion pair which then collapses (Scheme 2) [21,22]. 

Recently, Wallis and Kochi reported on the photochemical and thermal osmylation of benzene, substituted benzenes, naphthalene, and anthracene (331, 332). Complexes of the form Ar-0s04 are formed and were studied by laser flash photolysis. In the presence of donor... 

At the same time radical chemistry experienced a similar development. Except for extensive application in polymer chemistry, radical reactions were not considered generally useful synthetically. However, in these years fundamental studies in physical organic chemistry led to the establishment of a consistent picture of radical reaction kinetics, which triggered an explosion of synthetic applications in the 1980s (selected books and reviews [19-30]). Thanks to the ground-breaking studies by Kochi and others, the importance of transition metal chemistry for... 

Dihydroarcyriarubin C (104), a new bisindole alkaloid, has been isolated from fruit bodies of a myxomycete Arcyria ferruginea, which was collected at Hao, Yasu-cho, Kochi Prefecture, together with two known bisindoles, arcyriarubin C (2) and arcyriaflavin C (4), and the structure of 104 was elucidated by spectral data. Arcyriaflavin C (4) was also obtained, together with arcyriaflavin B (3), from fruit bodies of Tub if era casparyi, which ( 16839) was collected at Mt. Miune, Monobe-mura, Kochi Prefecture, in November 1997. Arcyriaflavin C (4) was revealed to exhibit cell cycle inhibition activity on HeLa cells on the basis of flow cytometry studies. Fruit bodies of Fuligo Candida, which ( 23446) was collected at Motoyama-cho, Kochi Prefecture, in August 2002, were revealed to contain a relatively high quantity of cycloanthranilylproline (105). 

Elegant studies by Kochi and co-workers111112 established that rapid ligand substitution according to Eq. (23) occurs when a slight oxidizing... 

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