Aluminum amalgam reductive cleavage

The aldehyde is also obtained by the hydroformylation of allylbenzene.6 An alternative method involves benzylation of 2-ethylthiazoline followed by reduction with aluminum amalgam and cleavage with mercuric chloride.( A sixth method of preparation is the phenylation of 2-vinyl-5,6-... 

In addition to deoxygenation sulfoxides undergo reductive cleavage at the carbon-sulfur bond when heated in tetrahydrofuran with aluminum amalgam. Keto sulfoxides were thus converted to ketones in usually quantitative yields (the keto group remained intact) [141]. 

The indolyl nitro compound (98) was converted to the corresponding nitrile oxide, which cyclized to afford an inseparable mixture of isoxazolidines (99) and (100 Scheme 2S).46 These were acetylated and the THP group replaced by a mesyl group at which point the desired 3-isomer could be separated. Elimination via a selenide intermediate provided the alkenylisoxazoline (101), which was converted to an isoxazolinium salt and reduced with LAH to give an N-methylisoxazolidine. Reductive cleavage with aluminum amalgam provided (+)-paliclavine. 

Reductive desulfurization of 9-(phenylsulfonyl)furo[2,3- ]quinoline and its 2-methyl derivative can be effected by treatment with LAH in THF solution at reflux, but proceeded poorly with aluminum amalgam, the reagent of choice for the reductive cleavage of vinyl sulfones <83JOC774>. Raney nickel was used to remove a thiomethyl substituent from the central ring of a furochromone direct precursor to visnagan <89JOC448l>. 

The reduction of aldols and ketols from the aldol condensation (method 102) is often a convenient route to branched 1,3-dio/s. Catalytic hydrogenation over platinum oxide, nickel-on-kieselguhr, and copper-chromium oxide has been used. Other procedures include electrolytic reduction and reduction by aluminum amalgam. 1,3-Diols may also be prepared by catalytic reduction of 1,3-diketones. Cleavage of the carbon-to-carbon and carbon-to-oxygen bonds accompanies this conversion. The effect of structure on the course of the reaction has been studied. ... 

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%)- ... 

Compound (1) and its enantiomer provide a variation on the same theme of stereospecific reductive amination. In this case, reduction of a chiral cyclic hydrazone (derived from an a-keto acid and (1)) with Aluminum Amalgam in wet DME proceeds with high stereoselectivity. Reductive cleavage of the N-N bond and ester hydrolysis complete the procedure, which produces a-amino acids with high optical purity (eq 4). The source of chirality is recovered by conversion of the resulting indoline-2-methanol back into (1). ... 

In the reductive cleavage of y-lactone 17, Naito et al. [17] reported that use of calcium in liquid ammonia at -70 °C enables the production of the desired carboxylic acid 18 as the sole product in 62% yield (Scheme 4.5). Other procedures including use of aluminum amalgam, chromium(II) chloride, and zinc in acetic acid led to complete recovery of the starting y-lactone 17. 

Sonication greatly helps in the reduction of C-0 single bonds by metals. An aromatic dioxolane ring reacts with lithium, sodium, or potassium with cleavage of the benzylic C-0 bond. The ring cleavage of epoxides by aluminum amalgam is effected in aqueous ethanol in the presence of sodium formate. Examples were studied with steroidic epoxy ketones (Eq. 25). 

The simplest conversion of the tosyl ester to the deoxysugar is by reductive cleavage. Although reduction with sodium amalgam or Raney nickel regenerates the primary hydroxyl group, the use of lithium aluminum hy-... 

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