Aluminum amalgam carbonyl compounds

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

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. 

Vinyl fluorides,1 Fluoro(phenylsulfonyl)methylithium (2), obtained by reaction of 1 with BuLi in THF at — 78°, reacts with carbonyl compounds to form fluorohydrins (3), which are dehydrated to (E)-a-fluoro-a,p-unsaturated sulfones (4) in 67-92% yield with CH3S02C1 or orthophosphoric acid. Conversion of 4 into vinyl fluorides (5) is effected with aluminum amalgam (—90% yield). The vinyl fluorides are obtained as a 1 1 mixture of (E)- and (Z)-isomers. 

On treatment with concentrated hydrochloric acid and aluminum amalgam, l-telluracyclohexane-3,5-diones decompose with elimination of tellurium. Their chemical behavior is determined by the presence of the dicoordinate tellurium center and two carbonyl groups in their molecules. As cyclic diketones, compounds 12 readily form oximes and dioximes under treatment with hydroxylamine. The former reaction is preferably carried out in dilute acetic acid solution, whereas the latter is carried out in basic... 

Another route to cyclic peroxides from carbonyl compounds is illustrated by the reaction of dichlorodiphenylmethane with hydrogen peroxide to form the dimeric benzophenone peroxide (77),62 which reacts with zinc in acetic acid to form benzopinacolone (Ph3C—CO— Ph), and with aluminum amalgam to form benzhydrol. On fusion (183-225°), 77 decomposes to form benzophenone. 

Sulfinyl and sulfonyl groups are easier to reduce than a-(aikylthio)carbonyl compounds. Aluminum amalgam has frequently been used for removal of sulfinyl and sulfonyl groups. This reagent is typically used in refluxing (wet) THF reduction of 3-keto sulfones can be carried out at room temperature by Na(Hg)x, if the solution is buffered with Na2HP04 ... 

Methylenation of carbonyl compounds. The reagent reacts with aldehydes and ketones in THF at 0° to give 0-hydroxy sulfoximines (2). On reduction of (2) with aluminum amalgam in aqueous THF containing acetic acid, reductive elimination occurs to give an olefin (3). 

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