Lithium with organometallic compounds

The most general synthetic route to ketones uses the reaction of carboxylic acids (or their derivatives) or nitriles with organometallic compounds (M.J. Jorgenson, 1970). Lithium car-boxylates react with organolithium compounds to give stable gem-diolates, which are decom-... 

The reaction of elemental sulfur with organometallic compounds is one of the standard methods of synthesis of thiols [3, 4], In this way, the ortho lithiation of lithium benzenethiolate led to the preparation of 1,2-benzenedithiol (1), and a convenient one-pot procedure which can be used on a large scale was worked out [5]. 

Pentamethylantimony was the first It6Sb species to be obtained by Wittig and Torssell in 1955 (104) Various other derivatives of this type have since been synthesized, and a range of preparative methods has been described. Among these are the alkylation of RiSbX, R3SbX2, and SbX species with organometallic compounds of lithium, magnesium, aluminum,... 

Not only lithium-derived organometallic compounds have proved to be suitable reagents for generating a new C —P bond Grignard and cadmium compounds have also found some applications, but they are not so widespread. For example, tris(pentafluorophenyl)phosphane (26) and bromobis(pentafluorophenyl)phosphane (27) both give ethy bis(pentafluoro-phenyl)phosphane (28) on reaction with ethylmagnesium bromide.12... 

Screttas and Eastham found that this base forms crystalline complexes with organometallic compounds of magnesium, lithium, and zinc. Thus on addition of a benzene solution of TED to a solution of butyllithium a crystalline complex separates the composition is BujLij —TED-Bu Lia. Triethylamine (1) and quinu-clidine (2) form similar complexes but they are considerably more soluble than the corresponding TED complex. 

In a series of studies over an extended period we found that this reaction is of uncommon synthetic and structural importance. Although it is best effected generally by the use of -butyllithium in ether, we showed that this exchange reaction proceeds with organometallic compounds of such metals as sodium, magnesium, barium, and aluminum. -In an examination of different solvents, we observed that low-boiling petroleum ether appears to be especially useful for reactions involving secondary and tertiary alkyl-lithium compounds which could not be prepared readily or used conveniently in ether solution. 

Reaction with Organometallic Compounds. Organo-magnesium (eq 4), lithium, and other main group metals readily undergo ligand transfer with PCI3 to form mono-, di-, or trialkyl(aryl) phosphines. A subclass of reactions include Aluminum Chloride-assisted transformations to form phosphetanes (eq 5). ... 

Organometallic compounds of copper were known for a long time before their versatil ity in synthetic organic chemistry was fully appreciated The most useful ones are the lithium dialkylcuprates which result when a copper(I) halide reacts with two equivalents of an alkyllithium in diethyl ether or tetrahydrofuran... 

Benzyne can also be generated from o-dihaloaromatics. Reaction of lithium amalgam or magnesium results in formation of a transient organometallic compound that decomposes with elimination of lithium halide. l-Bromo-2-fluorobenzene is the usual starting material in this procedure. 

Following fragmentation, the alkyl radical rapidly combines with a lithium atom to fonn the organometallic compound. 

Many other kinds of organometallic compounds can be prepared in a manner similar to that of Grignard reagents. For instance, alkyllithium reagents, RLi, can be prepared by the reaction of an alkyl halide with lithium metal. Alkyllithiums are both nucleophiles and strong bases, and their chemistry is similar in many respects to that of alkylmagnesium halides. 

E. Reacticms Involving Organometallic Compounds 1. Reaction of lithium alkyls with organic halides... 

The first example of chemically induced multiplet polarization was observed on treatment of a solution of n-butyl bromide and n-butyl lithium in hexane with a little ether to initiate reaction by depolymerizing the organometallic compound (Ward and Lawler, 1967). Polarization (E/A) of the protons on carbon atoms 1 and 2 in the 1-butene produced was observed and taken as evidence of the correctness of an earlier suggestion (Bryce-Smith, 1956) that radical intermediates are involved in this elimination. Similar observations were made in the reaction of t-butyl lithium with n-butyl bromide when both 1-butene and isobutene were found to be polarized. The observations were particularly significant because multiplet polarization could not be explained by the electron-nuclear cross-relaxation theory of CIDNP then being advanced to explain net polarization (Lawler, 1967 Bargon and Fischer, 1967). 

Other organometallic compounds that are hydrolyzed by water are those of sodium, potassium, lithium, zinc, and so on, the ones high in the electromotive series. Enantioselective protonation of lithium enolates and cyclopropyllithium compounds have been reported. When the metal is less active, stronger acids are required. For example, R2Zn compounds react explosively with water, R2Cd slowly, and R2Hg not at all, though the latter can be cleaved with concentrated HCl. How-... 

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