Adducts mercury

Benzo[h]thiophene sulfone (229) reacts as a vinyl sulfone and forms adducts (228) and (230) when treated with mercury(II) acetate in methanol and with cyclopentadiene, respectively. 

The iodide ion induced decomposition of trimethyl (trifluoromethyl) tin and of phenyl (trifluoromethyl) mercury represent additional interesting possibilities. The reaction of the tin reagent and iodide ion with (31, X = H) in refluxing glyme for 168 hr gives (32) and the corresponding 6jff,7j0-difluoromethylene adducts in 46% and 7% yields, respectively. ... 

Diethylzinc l,3-bis(l-adamantyl)imidazol-2-ylidene adduct is known (93JOM(462)13). Bis(l,3-diphenylimidazol-2-ylidene) mercury(II) carbene complexes follow from the corresponding imidazolium perchlorate and mer-cury(II) chloride (68AGE682). 

It was found out that when the bisfuranones 299 (R = H, Me, CMc3, TMS) were irradiated in a solution of acetone saturated with ethylene (medium pressure, 125 W, mercury lamp at —78°C), the biscyclobutane adducts 300, 301, and 302... 

Cacchi and Palmier (83T3373) investigated a new entry into the quinoline skeleton by palladium-catalyzed Michael-type reactions. They found that phenyl mercurial 134 was a useful intermediate for the synthesis of quinoline derivatives, and that by selecting the reaction conditions the oxidation level of the heterocyclic ring in the quinoline skeleton can be varied. On such example is shown in Scheme 16. PdCla-catalyzed coupling between organomercurial reagent 134 and enone 135 delivered adduct 136 which was subsequently cyclized to quinoline 137 under acidic conditions. 

Dichlorocarbene, generated by the action of 50 % potassium hydroxide on chloroform, adds to ethyl 1 W-azepine-l-carboxylate to furnish the all /rntu-trishomoazepine 12 in 35% yield280 (see Houben-Weyl, Vol. E 19b, p 1523). Subsequently, and as a result of a careful and detailed study of the addition of dichlorocarbene generated by the thermal decomposition of phenyl(trichloromethyl)mercury, it was deduced that carbene addition takes place sequentially in the order C4 —C5, C2—C3 and C6 — Cl. The intermediary mono- 10 and bis(dichlorocar-bene) 11 adducts have been isolated and characterized. 

A solution of 4.5 g (19.9 mmol) 4-(fm-butyldimethylsilyloxy)-2-cyclohexenone and 452 mg (1 mmol) of mercury(II) iodide is stirred at r.t. for 15 min and then cooled to — 78 °C. 5.03 g (24.8 mmol) of 1-ethoxy-1-(tm-bulyl(iimethylsilyloxy)ethene are added dropwise during 15 min. The mixture is stirred at — 78 °C for 2 h, quenched with 302 mg (3 mmol) of triethylamine and allowed to warm to r.t. The mixture is filtered through a short (3 cm) column of silica gel (deactivated with a 5% triethylamine solution in hexane/ethyl acetate, 10 1) eluting with hexane/ethyl acetate (10 1) and concentrated in vacuo. Purification of the crude material by flash chromatography (silica gel, hcxanc/cthyl acetate 30 1) gave the adduct as a colorless oil yield 7.98 g (18.7 mmol, 94%) d.r. (cisjtrans) 95.2 4.8. 

The low solubility of fullerene (Ceo) in common organic solvents such as THE, MeCN and DCM interferes with its functionalization, which is a key step for its synthetic applications. Solid state photochemistry is a powerful strategy for overcoming this difficulty. Thus a 1 1 mixture of Cgo and 9-methylanthra-cene (Equation 4.10, R = Me) exposed to a high-pressure mercury lamp gives the adduct 72 (R = Me) with 68% conversion [51]. No 9-methylanthracene dimers were detected. Anthracene does not react with Ceo under these conditions this has been correlated to its ionization potential which is lower than that of the 9-methyl derivative. This suggests that the Diels-Alder reaction proceeds via photo-induced electron transfer from 9-methylanthracene to the triplet excited state of Ceo-... 

The heavy alkaline earth metals Ca, Sr, and Ba react with 2 equivalents of NJ -bis(2,6-diisopropylphenyl)formamidine in the presence of bis(pentafluorophenyl)-mercury to afford the bis(formamidinato) species as THF adducts in good to moderate yield (Scheme 23). When the same reactions are carried out in a 1 1 molar ratio, N-p-tetrafluorophenyl-N,N -bis(2,6-diisopropylphenyl)formamidine is isolated as the sole product in all cases (Scheme 23). Other substituted N -bis(aryl)formamidinate complexes of the heavy alkaline earth metals were synthesized accordingly. ... 

Monoalkylthallium(III) compounds can be prepared easily and rapidly by treatment of olefins with thallium(III) salts, i.e., oxythallation (66). In marked contrast to the analogous oxymercuration reaction (66), however, where treatment of olefins with mercury(II) salts results in formation of stable organomercurials, the monoalkylthallium(III) derivatives obtained from oxythallation are in the vast majority of cases spontaneously unstable, and cannot be isolated under the reaction conditions employed. Oxythallation adducts have been isolated on a number of occasions (61, 71,104,128), but the predominant reaction pathway which has been observed in oxythallation reactions is initial formation of an alkylthallium(III) derivative and subsequent rapid decomposition of this intermediate to give products derived by oxidation of the organic substrate and simultaneous reduction of the thallium from thallium(III) to thallium(I). The ease and rapidity with which these reactions occur have stimulated interest not only in the preparation and properties of monoalkylthallium(III) derivatives, but in the mechanism and stereochemistry of oxythallation, and in the development of specific synthetic organic transformations based on oxidation of unsaturated systems by thallium(III) salts. 

Zinc dithiocarbamates have been used for many years as antioxidants/antiabrasives in motor oils and as vulcanization accelerators in rubber. The crystal structure of bis[A, A-di- -propyldithio-carbamato]zinc shows identical coordination of the two zinc atoms by five sulfur donors in a trigonal-bipyramidal environment with a zinc-zinc distance of 3.786 A.5 5 The electrochemistry of a range of dialkylthiocarbamate zinc complexes was studied at platinum and mercury electrodes. An exchange reaction was observed with mercury of the electrode.556 Different structural types have been identified by variation of the nitrogen donor in the pyridine and N,N,N, N -tetra-methylenediamine adducts of bis[7V,7V-di- .vo-propyldithiocarbamato]zinc. The pyridine shows a 1 1 complex and the TMEDA gives an unusual bridging coordination mode.557 The anionic complexes of zinc tris( V, V-dialkyldithiocarbamates) can be synthesized and have been spectroscopically characterized.558... 

Another remarkable example of a mercuracarborand halide adduct has been obtained by reaction of the octamethyl tetranuclear derivative 165 with [NMe4]F. This reaction affords complex [165-F]- in which the fluoride is coordinated to the four mercury centers in an approximate square-planar arrangement (Equation (57)). The Hg-F distances, which range from 2.56 to 2.65 A, are slightly longer than those found in [163-/i2-F]2. The 9Hg NMR resonance of the complex indicates coupling to the fluorine atom with 1Jug-F = 698 Hz.215... 

Interaction of 137 with dimethyl sulfide in 1,2-dichloroethane leads to the formation of the polymeric adduct [137-/t6-Me2S] , which features sandwiched dimethyl sulfide molecules (Figure 22).233 The sulfur atom of the latter interacts simultaneously with the mercury centers of two neighboring molecules of 137 and thereby achieves hexacoordination. 

The biphenyl, naphthalene, pyrene, and triphenylene adducts display intense room-temperature phosphorescence.237 238 These observations indicate the occurrence of a mercury heavy atom effect, which promotes... 

Application of catalysts allows sometimes executing this addition/elimination process even with alkenes without any electron-deficient substituent attached. Such case is illustrated by an example in Scheme 15. In the presence of mercury-(n) acetate and trifluoroacetic acid, 1,2,3-triazoles 146 react with vinyl acetate at 70 °G to give vinyl derivatives 148 in good yields (70-88%) <2002RJ01056>. Adducts 147 are presumed to be intermediates in this process. 

The C.-T. adduct Me2dazdt 2I2 (Me2dazdt = /V,/V -dimethylperhydrodiaze-pine-2,3-dithione, see Figure 10), which proved to be air-stable, was successfully reacted in THF at room temperature with gold(0)61 and palladium(0)62 in powder, and with liquid mercury 63 conversely, no reactivity of this adduct with platinum(0) and rhodium(O) was observed, even on refluxing the solvent. 

Subsequent isolation of solvomercuration products has supplied information about the stereoselectivity of the mercury addition and at the same time has shown that these reactions can give 1,2- and/or 1,4-addition products. In particular, the identification by XH NMR spectroscopy of a 1,4-adduct from 1,3-pentadiene and mercury(II)nitrate in methanol has provided155 the first direct evidence that oxymercuration of conjugated dienes can proceed by 1,4-addition. Furthermore, the observed Z,E-isomerization of the diene has shown that the 1,4-oxymercuration is a reversible process. 

Considering that /Tarninornercury(II) tetrafluoroborates are polar enough to undergo nucleophilic attack by the lone electron pair of an amine, ether or alcohol in the case of the 1,3-cyclooctadiene, 179, it has been assumed that the first formed 1,4-adduct can give the reaction product by displacement of mercury by amine with direct participation of the nucleophile in an assisted breakage of the anti C—Hg bond (path a) or by spontaneous reduction of mercury in the intermediate allylic organomercurial (path b) (equation 157). 

An alternative hypothesis, that the reaction product arises from a first formed 1,2-adduct, from which the same ionic intermediate may be generated (equation 158), has been ruled out by considering the directive effect of the conjugated double bonds on oxymercuration, which favors the attack of mercury at the terminal positions of conjugate 7r-systerns. 

Furthermore, more recent work about the monoalkoxymercuration of a series of conjugated dienes with different mercury salts has shown157 that the alkoxymercuration of these compounds proceeds in two steps, the first being the formation of 1,2-adducts in which, with the exception of the mercuration of a-terpinene, the alkoxy group occupies the allylic position. The 1,2-alkoxymercurials are in equilibria with the corresponding... 

Finally, the phenylsulfenylmercuration (using preformed mercury benzenesulfinate complex) of 1,3-dienes has also been reported158 to give 1,2- and 1,4-mercury adducts (equation 160). In most cases the reaction proceeds regioselectively to give 2-(phenylsul-fonyl)-l,3-dienes. 

Oxymercuration in dichloromethane at room temperature afforded the adducts 190 and 191 from 188 (equation 162), and 192 and 193 from 189 (equation 163), the electrophilic mercury attack preferentially occurring at the C(3) carbon atom. A similar selectivity was previously observed also in OM-DM of 188165. 

It has therefore been established170 from the product distributions that, while the oxymercuration is reversible, unless a base (e.g. sodium acetate) is added to the reaction medium, and gives almost exclusively the more stable compound 199, the aminomercu-ration takes place to give the kinetically controlled adduct 200, or under thermodynamic control the aminomercurial 201. Reactions are kinetically controlled when the mercurating species is a mercury(II) salt deriving from a weak acid such as mercury(II) acetate. Conversely, they are thermodynamically controlled with the covalent mercury(II) chloride. In the latter case, the presence of a strong acid in the medium allows the thermodynamically controlled product to be obtained. 

The photoreaction of polysilanes with Ceo has also been investigated [35]. Reaction (8.16) shows an example in which the irradiation in benzene with a low-pressure mercury-arc lamp afforded a product that contains 14wt% of Ceo into the polysilane chain. The incorporation of Ceo into the polysilane backbone has not been observed upon irradiation with X > 300 nm, when the cleavage of Si—Si bond does not take place. The adduct obtained from Reaction (8.16) has a lower oxidation potential than C6o( + 0-77 vs + 1.21 V) and a lower reduction potential than polysilane (—1.24 vs — 2 V). 

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