N-Mercury adducts

Sym. diorgano- via monoOrgano-mercury compounds Mercurysydnones—N-Mercury adducts s. 17,711 ... 

N-Mercury adducts 17, 711 Mercury(II) bromide 20, 258, 264 Mercury carboxylates... 

Sym. diorgano- via monodrgano-mercury compounds N-Mercury adducts... 

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. ... 

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... 

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. 

Further routes of cyclizations have been studied in parallel in the case of cis- and rra/J5-2-hydroxymethyl-l-cyclohexylamine (106) (880PP73). The preparation of thiourea or urea adducts 107 and 108 with phenyl isothiocyanate or phenyl isocyanate proceeds smoothly. The reaction of 107 with methyl iodide and subsequent alkali treatment, by elimination of methyl mercaptan, resulted in the iminooxazine 109 in high yields. The ring closures of both cis and trans thiourea adducts to 1,3-oxazines proceed with retention. Cyclodesulfuration of the adduct 107 by mercury(II) oxide or N,N -dicyclohexylcarbodiimide resulted in the iminooxazine 109, but the yield was low and the purification of the product was cumbersome. The ring closure of 108 with thionyl chloride led to the iminooxazine 109 in only moderate yield. 

Species containing mercury-nitrogen bonds, whether adducts or salts, are generally unstable in acid solutions, such bonds being broken by hydrogen ion to form the conjugate acids of the parent nitrogen compounds. With respect to stability in aqueous environment, therefore, the Hg—N bond lies between the Hg—F and Hg—O bonds on one hand and the Hg—C, Hg—S, Hg—I, and Hg—Br bonds on the other,... 

Halogenation of pyridines is easier than nitration or sulfonation because it can be carried out in nonacidic media and the pyridinehalogen adducts are appreciably dissociated. Dihalogenation can occur since one halogen atom causes little additional deactivation of the ring. The mercuration of pyridines (Section 3.2.1.4.9) probably involves initial coordination of the pyridine nitrogen to the mercury atom, and such coordination causes less ring deactivation than N-protonation. 

The mercury(II) adduct HgCl2(Et2N—N=N—NEt2), first reported by Fischer over 100 years ago (82), and the more recently described examples HgX2(R2N—N=N—NR2) (X = Cl, Br R = Ci 4 alkyl) (23,203), may well have similar N-l,N-3-chelate structures. 

With the adducts from mercury dichloride and acetylene, we [Nes-meyanov, Freidlina, Borisov (60-62)] began the investigation by studying the compounds of Biginelli and Jenkins for which either n or o-structures, or tautomerism between these might be assumed. 

The stereochemistry of addition of nucleophiles to Pd(II) cyclic diolefin adducts was next studied, and in all cases it was found to be trans (Section IV, A). However, strained diolefins such as norbornadiene tend to add nucleophiles exo, whereas the metal involved is held in the endo position. Thus, mercury(II) does not form strong n bonds and hydroxymercuration of norbornene is cis-exo (7, 262). However, the trans addition to unstrained olefins could not be explained in this way. 

Alkyl phenyl sulfones (piCj,27) are nearly as acidic as esters hence they are readily deprotonated by n-BuLi, LDA in THF, or EtMgBr in THF to give a-metalated sulfones. Their reaction with aldehydes gives a mixture of diastereomeric P-phenylsul-fone alkoxide adducts. Reductive elimination of the benzenesulfinate moiety from the adduct to produce the alkene is usually slow. To minimize side reactions, the hydroxyl group is first converted to an acetate, benzoate, mesylate, or /7-toluenesul-fonate and then treated with an excess of sodium amalgam [Na(Hg), prepared by adding small pieces of sodium to mercury] in methanol to furnish the trans-dlk n P... 

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