Boron methane

Carbanioas derived from the other above mentioned methane derivatives react with alkylboranes, bornic, and boronic esters, providing rich possibihties for the preparation of siagle-carbon iasertion products. Thus 2-aLkyl-l,3,2-dithiaborolanes are converted iato acids or thioacetals by trichloromethyllithium (335). 

Methane sulfonic acid, trifluoroacetic acid, hydrogen iodide, and other Brmnsted acids can faciUtate 3 -acetoxy displacement (87,173). Displacement yields can also be enhanced by the addition of inorganic salts such as potassium thiocyanate and potassium iodide (174). Because initial displacement of the acetoxy by the added salt does not appear to occur, the role of these added salts is not clear. Under nonaqueous conditions, boron trifluoride complexes of ethers, alcohols, and acids also faciUtate displacement (87,175). 

Boron oxide Bioaerosol Bitumen fume Bromotrifluoro methane Bromoxynil Bromoxynil octanoate Butadiene (1,3-butadiene)... 

Treatment of l-[2-(2-methoxy-5-isopropylphenyl)-l-hydroxyethyl]-2,6,6-tri-methylcyclohexene with triethylsilane and boron trifluoride etherate in dichloro-methane at —10° leads to its reduction to 2-(2,6,6-trimethyl-l-cyclohexenyl)-l-(2-methoxy-5-isopropylphenyl)ethane in 69% yield (Eq. 36).174... 

The reactivity of the closely related system TpMe2PtMeH2 toward electrophiles in arene solvents has also been reported recently (68). The boron-based Lewis acid B(C6F5)3 induced elimination of methane and formation of an aryl(dihydrido) platinum(IV) complex via arene C-H activation (Scheme 17, A -> C). The active acid may be either B(C6F5)3 or alternatively a proton generated from B(C6F5)3 and trace water. It was proposed that the acid coordinates to a pyrazole nitrogen (shown in Scheme 17, B) forming an intermediate five-coordinate platinum(IV) complex, which readily eliminates methane. 

Another interesting observation in this study is the boron trifluoride etherate-catalyzed rearrangement of tri-ir-methane systems 141 that afford the corresponding cyclopentenes 142. These reactions can be considered as the first examples of tri-ir-methane rearrangements in the ground state. Interestingly, compounds 141 only undergo conventional di-TT-methane reactions on irradiation. The mechanism shown in Scheme 25 is proposed to account for this novel reaction [79]. 

Hunt s group (50, 51) have pioneered the application of the Cl source to organometallics such as the iron tricarbonyl complex of heptafulvene, whose electron impact spectrum shows (M—CO)+ as the heaviest ion, in contrast to the methane Cl spectrum with the ion as base peak. Boron hydrides (52) and borazine (53) have also been studied. The methane Cl spectrum of arenechromium and -molybdenum (54) show protonation at the metal giving a protonated parent or molecular ion. Risby et al. have studied the isobutane Cl mass spectra of lanthanide 2,2,6,6-tetramethylheptane-3,5-dionates[Ln(thd)3] (55) and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-oetanedione [H(fod)] lanthanide complexes (56). These latter complexes have been suggested as a means of analysis for the lanthanide elements. 

Chiral cyclic boronic esters with (dichloroniethyl)lithium at —100 C form borate complexes4. Borate complexes cart also be formed by generation of (dichloromethyl)lithium from dichloro-methane and lithium diisopropylamide in the presence of a boronic ester at —78 C to — 5 C (Section 1.1.2.1.2.2,)28,19. In situ generation of (dibromomethyl)lilhium is required for preparing a-bromo boronic esters (see Sections 1.1.2.1.1.2. and 1.1.2.1.3.2.). 

Compounds with H H—H Hydrogen H—Be—H Beryllium hydride H—B—H Boron hydride H 1 H—C—H 1, Methane H—N—H Ammonia H— H Water H—F Hydrogen fluoride... 

One popular method that has been apphed to industrial processes for the enantio-selective reduction of prochiral ketones, leading to the corresponding optically active secondary alcohols, is based on the use of chiral 1,3,2-oxazaborolidines. The original catalyst and reagent system [diphenyl prolinol/methane boronic acid (R)] is known as the Corey-Bakshi-Shibata reagent. Numerous examples... 

Nitrosonium tetrafluoroborate has been prepared from nitrosyl fluoride (NOF) and boron trifluoride in Freon-113. With this reagent, in a nitro-methane solution, pyridine was converted into jV-nitrosopyridinium tetra-fluorobate, m.p. 155°-158°C [33]. 

The first polymerizations reported by Kops and Schuerch147 were those of l,4-anhydro-2,3,6-tri-0-methyl-/3-D-galactopyranose and 1,4-anhydro-2,3-di-0-methyl-a -L-arabinopyranose. The latter compound was slightly contaminated with l,4-anhydro-2,3-di-0-methyl-a-D-xy-lopyranose, but the course of the polymerization could nevertheless be monitored reasonably accurately. For the most part, the polymerizations were conducted at 10% concentration (g/mL) in dichloro-methane, or aromatic hydrocarbons, with 1-5 mol% of phosphorus pentafluoride, or boron trifluoride etherate. At low temperature (—78 to —97°), the d.p. of both polymers produced was —90 at increasing temperatures of polymerization, termination processes became more severe, and the d.p. lower. Usually, the reaction times were long (perhaps unnecessarily so), and the conversions were 50 to 90%. The specific rotations of the D-galactans prepared at —28 and —90° differ by only —10° ( — 85 to — 95°), but those of the L-arabinans varied from + 6... 

The Onsager theory of geminate recombination was qualitatively consistent for aryl-substituted thiapyrylium salt and dialkylamino-substituted triphenyl-methane dispersed in polycarbonate film [301]. The quantum yield of Hie photogeneration was equal to 0.5 at the electric field strength of 106 V cm-1, mobility of I0 12m2 V-1 s-1. Hole and electron conductivity was established. In a triphenylamine-lexan system doped with a boron diketone acceptor, the... 

When 2-hydroxymethyl-5,6-methylenedioxybenzo[6]thiophene is heated in a polar solvent with a catalytic amount of mineral acid, the polycyclic compound (166) is formed in 75% yield, probably by way of the intermediate (251).190 3-Hydroxymethylbenzo[6]thiophene and di(3-benzo[6]thienyl)methane react together in the presence of boron trifluoride to give a compound with the probable structure 252.486... 

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