Dietmar Seyferth

Halomethyl—metal compounds L. Preparation of monohalomethyl derivatives of germanium, tin, lead and mercury via halomethylzinc halides☆☆☆

The reaction of iodomethylzinc iodide or bromomethylzinc bromide in THF with the appropriate metal or organometallic halide was used in the present ation of Me3SnCH2I, Me3SnCH2Br, Me2Sn(CH2I)2, Me2Sn(CH2Br)2, Me2PhSnCH2I, Ph3SnCH2I, Sn(CH2I)4, Ph3PbCH2I, Hg(CH2I)2 and Hg(CH2Br)2. In most cases the product yields were very good. The reaction of iodomethylzinc iodide with trimethylchlorogermane gave in low yield both Me3GeCH2I and Me3GeCH2GeMe3. These compounds were obtained in much better yield when ICH2ZnI was allowed to react with germanium tetrachloride and the reaction product was methylated with MeMgBr. The reaction of iodomethyl-tin compounds with silver chloride and bromine in acetonitrile served well in the preparation of Me3SnCH2Cl, Me3SnCH2Br, Me2Sn(CH2Cl)2, Me2Sn(CH2Br)2 and Me2PhSnCH2Cl. Experiments in which mixtures of Et3SiD and n-Bu3SiH were allowed to react with ICH2ZnI in refluxing ether or with Hg(CH2I)2/Ph2Hg in refluxing benzene gave only Et3SiCH2D and n-Bu3SiCH3. This eliminates from consideration the possibility that these reactions proceed by a two-step alkylation-reduction or reduction-alkylation sequence.

The preparation of functional alkylidynetricobalt nonacarbonyl complexes from dicobalt octacarbonyl

Abstract Various functionally-substituted methylidynetricobalt nonacarbonyl derivatives, RCCo3(CO)9, where R is D, Me3Si, PhMe2Si, (MeO)2P(O), (EtO)2P(O), Me3COC(O), Me3SiOC(O), Et2NC(O), CH3C(O), C2H5C(O), n-C3H7C(O), Me2-CHC(O), n-C4H9C(O), Me3C(O), PhC(O), p-CH3C6H4C(O), p-BrC6H4C(O), HOCH2, HC(O), CH3O and Me2N, have been prepared by reaction of dicobalt octacarbonyl with the appropriate RCX3 or RCHX2 (XCl or Br) compound.

The Preparation of Organolithium Compounds by the Transmetalation Reaction. I. Vinyllithium1,2

The transmetalation reaction occurring between phenyllithium and tetravinyltin (4: 1 molar ratio) in ether produces vinyllithium in good yield. A similar reaction occurs between n-butyllithium and tetravinyltin in pentane; in this case solid vinyllithium precipitates. Vinyllithium is more stable in ether and tetrahydrofuran solution than are nbutyllithium or phenyllithium. The use of vinyllithium in the preparation of a number of previously known vinyl compounds, as well as of the new STAB(CH = CH/sub 2/)/sub 4/!/sup -/ and STAB(CH ~ CH/sub 2/ ) (C/sub 6/H/sub 5/)/sub 3/!/sup -/ ions, is described. (auth)

Halomethyl-metal compounds : XL. Trimethylsilyl-substituted bromomethyllithium and -magnesium reagents. Trimethyltindibromomethylmagnesium chloride

Abstract The low temperature reactions of n-butyllithium with trimethyl(tribromomethyl)silane, trimethyl(dibromomethyl)silane and bis(trimethylsilyl)dibromomethane served well in the preparation of trimethylsilyldibromomethyllithium, trimethylsilylbromomethyllithium and bis(trimethylsilyl)bromomethyllithium, respectively. The low temperature reaction of isopropylmagnesium chloride in THF with trimethyl(tribromomethyl)silane and trimethyl(tribromomethyl)tin gave the trimethylsilyldibromomethylmagnesium chloride and trimethyltindibromomethylmagnesium chloride reagents. Reactions of these lithium reagents with trimethylchlorosilane, trimethyltin chloride, mercuric halide, dimethyl sulfate and water are described. The action isopropylmagnesium chloride in THF on trimethyl(dibromomethyl)silane, trimethyl(diiodomethyl)silane and bis(trimethylsilyl)dibromomethane led principally to reduction to the respective monohalo compounds. The new Grignard reagents, diiodomethylmagnesium chloride and bromochloromethylmagnesium chloride, and their reactions with trimethylchlorosilane are reported. Trimethyl(bromodichloromethyl)silane was prepared in good yield by bromination of trimethyl(dichloromethyl)silane, while bromination of trimethyl(dibromomethyl)silane with N-bromosuccinimide gave trimethyl(tribromomethyl)silane in high yield.

Halomethyl—metal compounds : LXXII. The preparation of α-halocyclopropyl derivatives of lithium and their application in the synthesis of α-halocyclopropyl compounds of silicon, germanium, tin, lead, and mercury. A novel isomerization of syn-7-bromo-anti-7-lithionorcarane to the anti-7-bromo-syn-7-lithio isomer☆

Abstract A number of α-bromocyclopropyllithium reagents have been prepared at low temperature (−90° to −100°) in THF or THF/Et2O medium by reaction of n-butyllithium with the respective gem-dibromocyclopropane. Reactions of these new lithium reagents with concentrated HCl, trimethylchlorosilane, dimethyldichlorosilane, trimethyltin chloride, dimethyltin dichloride, dimethyldichlorogermane, trimethyllead bromide, mercuric chloride and some other organometallic halides are described. A novel isomerization of syn-7-bromo-anti-7-lithionorcarane to anti-7-bromo-syn-7-lithionorcarane, induced by the presence of a slight excess of 7,7-dibromonorcarane, is described.

Chemistry of Carbon-Functional Alkylidynetricobalt Nonacarbonyl Cluster Complexes

Publisher Summary The chapter discusses principally the chemistry of carbon-functional alkylidyrietricobalt nonacarbonyl complexes. Steric hindrance plays an important role in the chemistry of alkylidynetricobalt nonacarbonyl. The alkylidynetricobalt nonacarbonyl complexes all are highly colored, with colors ranging from red to purple to brown to black, depending on the apical substituent. The general chemical reactivity of the alkylidynetricobalt nonacarbonyl includes instability toward attack by oxidizing agents and many basesand nucleophiles. The chapter describes other cluster complexes in which a tetrahedral core of 1 carbon and 3 metal atoms is present. Such complexes in which the nickel atoms are nickel, ruthenium, and osmium are presented in this chapter. Their chemistry remains largely unexplored, except for the transformations of compound XV in strong acid medium. The sensitivity of these cluster complexes to diverse bases, nucleophiles, and oxidizing agents will seriously limit the chemistry that can be carried out, but even with these limitations it should be possible to continue a broad development of the organo-functional interconversions of these complexes.

Trimethylsilyl-substituted diazoalkanes : I. Trimethylsilyldiazomethane

Abstract Trimethylsilyldiazomethane was prepared by the action of aqueous KOH on nitroso-N-(trimethylsilylmethyl)urea. The spectroscopic properties of this stable, greenish-yellow liquid which can be isolated by gas chromatography are discussed. Its reaction with acetic acid gives the expected CH3CO2CH2SiMe3 in addition to SiC cleavage products, CH3CO2CH3 and CH3CO2SiMe3. Products of the 1,3-dipolar addition of Me3SiCHN2 to activated olefins were not very stable, and only the adduct with acrylonitrile was isolated as a pure material Trimethylsilyldiazomethane undergoes Me3SiCH transfer to olefins, giving trimethylsilyl-substituted cyclopropanes, in the presence of CuCI in benzene, but other products are formed as well. Thus such a reaction with cyciohexenegave anti-7-trimethylsilylnorcarane (65%), syn-7-trimethylsilylnorcarane (7%), cis- and trans-l,2-bis(trimethylsilyl)ethylene (9% and 13%, respectively), and an unidentified Me3SiCH trimer (2.3%).

Halomethyl—metal compounds : LXIII. Diethyl lithiodichloromethylphosphonate and tetraethyl lithiochloromethylenediphosphonate☆

Abstract The action of n-butyllithium in THF at low temperature on diethyl trichloromethylphosphonate and tetraethyl dichloromethylenediphosphonate gave the reagents LiCCl 2 P (O) (OEt) 2 and [(EtO) 2 (O)P] 2 CClLi, respectively. The hydrolyses of these reagents, some coupling reactions with dimethyl sulfate, allyl bromide and trimethylchlorosilane and their use in the synthesis of chloroolefins are described.

Halomethyl-metal compounds XX. An improved synthesis of phenyl(trihalomethyl)mercury compounds

Abstract The preparation of PhHgCClnBr3−n (n = 0–2) in good yield can be accomplished by the reaction of phenylmercuric chloride, the respective haloform and the tert-butanol monosolvate of commercial, unsolvated potassium tert-butoxide in ca. 1/1/1.4 molar ratio in tetrahydrofuran solution at -25°. This represents a significant improvement over the previous procedure (ref. 7) in that a high speed stirring apparatus is not required, commercial potassium tert-butoxide may be used and large excesses of the haloform are not necessary.

Studies in phosphinemethylene chemistry : XIII. Routes to triphenylphosphine-halomethylenes and -dihalomethylenes☆

Abstract The action of phenyllithium on (bromomethyl)triphenylphosphonium bromide results in a nearly equimolar mixture of triphenylphosphinebromomethylene (formal H ÷ abstraction) and triphenylphosphinemethylene (formal Br ÷ abstraction). With (iodomethyl)triphenylphosphonium iodide a mixture of triphenylphosphineiodomethylene and triphenylphosphinemethylene is formed in which the latter is favored by a factor of about three. A new route to haloolefins based on phenyl(halomethyl)mercurial reagents is summarized by the equations below (X  Cl and Br). C 4 H 3 HgCX 2 Br ÷ (C 6 H 5 ) 3 P ÷ RR′CO → RR′CCX 2 ÷ C 6 H 5 HgBr ÷ (C 6 H 5 ) 3 PO C 6 H 5 HgCHXBr ÷ (C 6 H 5 ) 3 P ÷ RR′CO → RR′CCHX ÷ C 6 H 5 HgBr ÷ (C 6 H 5 ) 3 PO