Sodium amalgam reductive cleavage

The methyl-vomicinium salts must now be formulated as CCXLV in accord with the iV -methylpseudostrychnine methiodides. On catalytic hydrogenation (330a) two stereoisomers of structure CCXLVI are formed as well as a mole of methanol, in accordance with the Emde cleavage described above. The sodium amalgam reductive cleavage... 

The ligands with S2C donor atom sets have been found only in complexes and cannot be isolated in the free state. Sodium amalgam reduction of mononuclear [Ni(S4C3Me2)J leads to removal of benzenedithiolate and formation of trinuclear [Ni(p-S2C3Me2)]3 (Eq. 1) (10). The trinuclear complex shows cleavage and insertion reactions of interest as CO dehydrogenase model reactions (see below). Tetrahydrofurane = THF. 

Reductive cleavages of carbon-chlorine bonds by active metals and with photochemical activation figure in recent studies aimed at HFCs and HCFCs Sodium amalgam [3J] (equation 25), zinc powder [34] (equation 26), and alumi-mun/tin chloride [35] (equation 26) are all used in conjunction with protic solvents in reactions giving high yields and conversions... 

Attempts to prepare this substance by reduction of dioxotetrahydro-1,3,5-triazine with sodium amalgam,hydroiodic acid, or tin in acetic acid, were accompanied by hydrolytic cleavage of the ring. Only... 

Similar results were obtained on reduction of 3,4,5-trimethylisoxa-zole/ Further examples of such a cleavage were found later. Thus, j8-(3-halogenoisoxazol-5-yl) propionic acids (163) on treatment with sodium amalgam give a mixture of S-cyano-y-ketovaleric and succinic acids (163—> 164) The reaction can be interpreted as a result of... 

Subsequently, Julia, Uguen and Callipolitis104 105 used both lithium metal in ethyl-amine and sodium amalgam in ethanol to effect reductive cleavages of j8-hydroxysulphones or of allylic sulphones. The latter reaction is part of a synthetic sequence for the construction of alkenes that has been used with some considerable success... 

Partial reduction of the aromatic ring is especially easy in anthracene-9-carboxylic acid which was reduced to 9,10-dihydroanthracene-9-carboxylic acid with 2.5% sodium amalgam in aqueous sodium carbonate at 10° in 80% yield [987]. Aromatic carboxylic acids with hydroxyl groups in the ortho positions suffer ring cleavage during reductions with sodium in alcohols and are converted to dicarboxylic acids after fission of the intermediate j8-keto acids. 

Sodium-naphthalene reduction of organotrineopentoxyphosphonium salts led to the instantaneous loss of phosphonium ion phosphonates and phosphites were obtained748 (reaction 224). Alkali metal amalgams are efficient reagents for the reductive cleavage of both achiral and optically active phosphonium salts configuration is retained750 (Table 23). 

Reduction of a,P-unsaturated sulfones.1 Sodium amalgam (7, 326-327) is not satisfactory for reductive cleavage of alkenyl sulfones, R CH=CR2S02C6H5. These substrates are best reduced to alkcncs wth potassium-graphite (65-85% yields). 

EMDE DEGRADATION. Modification of the Hofmann degradation method for reductive cleavage of the carbon-nitrogen bond by treatment of an alcoholic or aqueous solution of a quaternary ammonium halide with sodium amalgam. Also used as a catalytic method with palladium and platinum catalysts. The method succeeds with ring compounds not degraded by the Hofmann procedure. 

Certain aryl-substituted a- and /S-amino Intones have been successfully reduced to amino alcohols by catalytic hydrogenation over palladium, platinum, or nickel catalysts. Cleavage of the carbon chain sometimes occurs during catalytic hydrogenation of /S-amino ketones. Fair yields of the amino alcohols ate obtained in these cases by reduction with sodium amalgam in dilute acid or aluminum amalgam and water. /S-Amino aldehydes from the Mannich reaction (method 444) are reduced in excellent yields to amino alcohols by lithium aluminum hydride or by catalytic hydrogenation over Raney nickel. Lithium aluminum hydride reduces diazo ketones to 1-amino-2-alkanols (93-99%)- ... 

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