First studies with methyl

The first study with an oxygen compound which was sufficiently rigorous to provide evidence on the question of co-catalysis was that of Farthing and Reynolds [61]. They showed that 3,3-bischloromethyl oxetan could be polymerised in methyl chloride solution by boron fluoride only in the presence of water. Tater, Rose [62] obtained kinetic evidence for the need for a co-catalyst in the system oxetan—boron fluoride—methyl chloride, and he interpreted the low reaction rate when no water was added as due to residual water he also showed that water and a hydroxyl-terminated polymer could act as co-catalysts. 

The first kinetic results in the area were obtained by studying the quatemization of 4-alkyl-, 5-alkyT, and 2-alkylthiazoles with methyl iodide (253-255). A deeper and more exhaustive study of this reaction has been carried out recently with more elaborate substrates (152). 

The 2-methyl-4,9-dioxo-4,9-dihydrothiazolo[4,5-.g]quinoline was first quar-temized with methyl iodide on pyridine nitrogen and then treated with IV-methyl-quinolinium-4-yl salt, affording monomethine cyanine dyes 41 to study solva-tochromism, acid-base properties, and antimicrobial activities (95MI1). 

Developmental Effects. Adverse effects of methyl parathion on hirman fetal development have not been reported. Based on studies in animals, such effects appear to be possible if pregnant women were exposed during the first trimester to high concentrations of methyl parathion that resulted in significant depression of cholinesterase levels, particularly if concomitant signs and symptoms of organophosphate intoxication occur. Such an exposure scenario may occur with occupational exposure, exposure in homes or offices illegally sprayed with methyl parathion, or accidental exposure to methyl parathion, but is less likely as a result of low-level exposure. 

As the phosphonium diylides, lithium phosphonium yldiides, first described by Schlosser and Corey (Ph3P=CR-Li R=H, C3H7) [60-62], have a high nucleophilicity and reactivity. Recently, the a-silylated lithium phosphonium yldiide 20 has been prepared from the stable phosphanyl-(silyl)carbene 19 and alkyl-lithium (Scheme 13). The first crystal X-ray diffraction study of such a reagent was proposed for 20 and its reaction with methyl iodide or phosphorus elec-... 

A mechanistic study of the reaction of sulphoxides with the sodium salt of 1 -methyl-1 -phenylethyl hydroperoxide in benzene-alcohol solutions at room temperature showed that the reaction is first order with respect to sulphoxide and the hydroperoxide salt. The rate was also shown to be inversely proportional to the alcohol concentration in the solvent and this dependence was shown to increase with increasing pH. Also, more sterically crowded alcohols caused a decreased rate of reaction. 

Nucleophilic Trapping of Radical Cations. To investigate some of the properties of Mh radical cations these intermediates have been generated in two one-electron oxidant systems. The first contains iodine as oxidant and pyridine as nucleophile and solvent (8-10), while the second contains Mn(0Ac) in acetic acid (10,11). Studies with a number of PAH indicate that the formation of pyridinium-PAH or acetoxy-PAH by one-electron oxidation with Mn(0Ac)3 or iodine, respectively, is related to the ionization potential (IP) of the PAH. For PAH with relatively high IP, such as phenanthrene, chrysene, 5-methyl chrysene and dibenz[a,h]anthracene, no reaction occurs with these two oxidant systems. Another important factor influencing the specific reactivity of PAH radical cations with nucleophiles is localization of the positive charge at one or a few carbon atoms in the radical cation. 

Because salts of the [Rh(CO)2X2] ion are not only simple to prepare but rather stable species under ambient conditions, the reaction of [Rh(CO)2X2] ions with methyl iodide can be readily studied. Infrared spectroscopy at room temperature (15) reveals that an acetyl complex of rhodium(III) is the first detectable species after reaction. This species was isolated as its trimethylphenylammonium salt, and the structure of this material has been determined by X-ray crystallography (16). The... 

In the context of Pmp-containing tripeptide derivatives, the 3-indol-l-yl-pro-pyl analogue turned out to exhibit high affinity. Substituting the indol 5-posi-tion with methyl or hydroxyl resulted in compounds 41 and 42 with subnanomolar IC50 values (Scheme 7). These have been the first compounds of SH2 domain antagonists with subnanomolar affinity reported. These systematic studies enabled Novartis to push further analogues into in vivo studies [148,... 

The first microscopical computation of a free energy curve for a chemical reaction in solution was performed by the Jorgensen s group [41,52,53] ten years ago. They studied the degenerate SN2 reaction of chloride anion with methyl chloride in gas phase, in aqueous solution and in dimethylformamide (DMF) ... 

The first successful results of the asymmetric Michael addition under phase transfer catalyzed conditions were achieved by use of ingeniously designed chiral crown ethers 13 and 52.1441 The 3-keto ester 49 reacted with methyl vinyl ketone by use of 13 to give the Michael product 50 with excellent enantioselectivity but in moderate yield, as shown in Scheme 18. The Michael addition of methyl 2-phenylpropionate 51 to methyl acrylate afforded the diester 53 by use of another crown ether 52 in good yield with good enantioselectivity.1441 Various chiral crown ethers were studied to... 

A photolytic study with a 5-azidotetrazole derivative also led to the formation of a tetrazolo[l,5-/z]quinazoline compound, although the yield was fairly low. Araki et al. published findings that irradiation of 110 in aqueous medium resulted in formation of the mesoionic enolate 112 in 8% yield <2000JHC1129> (Scheme 20). The authors concluded that the formation of the tricyclic structure can be rationalized by an intramolecular insertion of the triplet nitrene formed from 110 to a C-H bond of an ortho-methyl group to give at first intermediate 111, which was converted under the applied reaction conditions to produce 112. 

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