Aluminum amalgam, reduction

The sonochemical-promoted aluminum amalgam reduction of P-nitro alcohols provides an improved yield and accelerated conversion to the corresponding amino alcohols.108... 

REDUCTION WITH ALUMINUM AMALGAM Reduction of Aliphatic-Aromatic Ketones to Pinacols [144]... 

The electrophilic substitution of the 3-aryl compounds (265, R = Ar, R = H) exemplified by the formation of 5-bromo- (265, R = Ar, R = Br) and 5-nitro derivatives (265, R = Ar, R = NOj) has been put forward as evidence against the meso-ionic formulation 265. lliis approach is unacceptable since ground state charge distribution cannot be deduced from reaction products. The aluminum-amalgam reduction of meso-ionic l,2,3-thiadiazol-4-ones (265) yields either N-mercaptoacetyl-A-arylhydrazines or Ar-acyl-A-arylbydrazines. Triethyl-oxonium tetrafluoroborate and meso-ionic l,2,3-thiadiazol-4-ones (265) yield 1,2,3-thiadiazolium tetrafluoroborates (267). The effect of solvent on the ultraviolet spectra of meso-ionic l,2,3-thiadiazol-4-ones (265) has been reported. ... 

The Julia olefin synthesis consists of the reaction of a sulfonyl anion with an aldehyde or ketone. The resulting alcohol is usually acetylated and the olefin formed by aluminum-amalgam reduction. The yield of / -hydroxysulfone is usually good, but the subsequent reductive elimination is more... 

The reactivity and chemistry of tetrahydro-3,6-pyridazinediones has not been much investigated. The parent compound (cyclic succinhydrazide) has been obtained by aluminum amalgam reduction of maleic hydrazide. Attempts to prepare it by alternative methods were unsuccessful (Section III,D). It forms a A,A-dimethyl or diacetyl and a A-monoethyl derivative with benzenesulfonyl... 

Aluminum amalgam reduction of triorganochlorostannanes forms the hydrides in < 60% yields ... 

Berlin, K.D., Claunch, R.T., and Gaudy, E.T., a-Aminoarylmethylphosphonic acids and diethyl a-aminoarylmethylphosphonate hydrochlorides. Aluminum-amalgam reduction of oximes of diethyl aroylphosphonates, J. Org. Chem., 33, 3090, 1968. 

Aluminum amalgam reductions are generally carried out in aqueous THF solutions (typically 10% aqueous THF) at higher temperatures (from 0° to reflux conditions) than those generally employed for Na/Hg desulfonylations. Aluminum amalgam is not commercially available but is easily prepared by immersion of aluminum foil into a 2% aqueous solution of HgCl2.18... 

Reduction of dihyro compounds to the tetrahydro derivatives is sometimes possible. For example, thiazolines are reduced to thiazolidines by aluminum amalgam. 

Benzopinacol has been prepared by the action of phenylmag-nesium bromide on benzil 1 or methyl benzilate. Usually it has been obtained by reduction of benzophenone, the reducing agents being zinc and sulfuric acid or acetic acid, aluminum amalgam, and magnesium and magnesium iodide. The present... 

C. Reduction of )3-Keto Sulfoxides with Aluminum Amalgam (//)... 

Metal-induced reductive dimerization of carbonyl compounds is a useful synthetic method for the formation of vicinally functionalized carbon-carbon bonds. For stoichiometric reductive dimerizations, low-valent metals such as aluminum amalgam, titanium, vanadium, zinc, and samarium have been employed. Alternatively, ternary systems consisting of catalytic amounts of a metal salt or metal complex, a chlorosilane, and a stoichiometric co-reductant provide a catalytic method for the formation of pinacols based on reversible redox couples.2 The homocoupling of aldehydes is effected by vanadium or titanium catalysts in the presence of Me3SiCl and Zn or A1 to give the 1,2-diol derivatives high selectivity for the /-isomer is observed in the case of secondary aliphatic or aromatic aldehydes. 

That propargylic starting materials are often employed in modern allene hydrocarbon chemistry is not surprising and the following examples are just a small selection from a much larger synthetic effort. Thus, the sulfones 61 are first cleaved in an aluminum amalgam-mediated reduction to the intermediates 62, which lose sulfur dioxide under the reaction conditions and furnish the trisubstituted allenes 63 in good to excellent yields (75-95%) (Scheme 5.7) [18]. 

A different approach to the stereospecific synthesis of sulfinamides described by Johnson (117,118) is based on the conversion of suitable chiral tetracoordinate sulfur compounds into sulfinamides. It was shown (117) that optically active methyl phenyl sulfoximide undergoes a clean and stereospecific reduction to the corresponding sulfinamide by means of aluminum amalgam. On the other hand,... 

Oxidative cyclization, substituted stil-benes to phenanthrenes, 46, 91 Oximes, reduction with lithium aluminum hydride, 48, 23 Oximinomalononitrile, from nitrosation of malononitrile, 48,1 reduction with aluminum amalgam, 48,2 ... 

B. N-t-Butylhydroxylamine. Caution Since hydrogen may he liberated during the reduction with aluminum amalgam, the reaction should he conducted in a hood. Also, the aluminum amalgam may he pyrophoric. Consequently, it should he used, immediately and not allowed to become dry. 

Reductions with aluminum are carried out almost exclusively with aluminum amalgam. This is prepared by immersing strips of a thin aluminum foil in a 2% aqueous solution of mercuric chloride for 15-60 seconds, decanting the solution, rinsing the strips with absolute ethanol, then with ether, and cutting them with scissors into pieces of approximately 1 cm [141,142]. In aqueous and non-polar solvents aluminum amalgam reduces cumulative double bonds [143], ketones to pinacols [144], halogen compounds [145], nitro compounds [146, 147], azo compounds [148], azides [149], oximes [150] and quinones [151], and cleaves sulfones [141, 152, 153] and phenylhydrazones [154] (Procedure 30, p. 212). 

Nitroso compounds are usually not obtained directly but rather by reoxidation of hydroxylamino compounds or amines. Hydroxylamino compounds are prepared by electrolytic reduction using a lead anode and a copper cathode [573], by zinc in an aqueous solution of ammonium chloride [574 or by aluminum amalgam [147], generally in good yields. 

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