Aldehydes from carbonylation

A novel approach to the asymmetric synthesis of epoxides, allylic alcohols, a-amino ketones, and a-amino aldehydes from carbonyl compounds through a,/i-epoxy sulfoxides using the optically active p-tolylsulfmyl group to induce chirality./. Org. Chem. 1989, 54, 3130-3136. 

This pattern of increased reactivity resulting from carbonyl group prolonalion has been seen before m nucleophilic additions to aldehydes and ketones (Section 17 6) and... 

Nitro alcohols form salts upon mild treatment with alkahes. Acidification causes separation of the nitro group as N2O from the parent compound, and results in the formation of carbonyl alcohols, ie, hydroxy aldehydes, from primary nitro alcohols and ketols from secondary nitro alcohols. 

Ethylene oxide reacts with phosphonium haUdes to give yUdes, which are used to synthesize olefins from carbonyl compounds, such as aldehydes and ketones (92). 

Gordon used a household microwave oven for the transfer hydrogenation of benz-aldehyde with (carbonyl)-chlorohydridotris-(triphenylphosphine)ruthenium(II) as catalyst and formic acid as hydrogen donor (Eq. 11.43) [61]. An improvement in the average catalytic activity from 280 to 6700 turnovers h-1 was achieved when the traditional reflux conditions were replaced by microwave heating. 

Another factor complicating the situation in composition of peroxyl radicals propagating chain oxidation of alcohol is the production of carbonyl compounds due to alcohol oxidation. As a result of alcohol oxidation, ketones are formed from the secondary alcohol oxidation and aldehydes from the primary alcohols [8,9], Hydroperoxide radicals are added to carbonyl compounds with the formation of alkylhydroxyperoxyl radical. This addition is reversible. 

Murai and coworkers reported on operationally simple aldol reactions with lithium enolates generated from carbonylation of silylmethyl lithium species [57]. Upon 1,2-silicon shift, a-silyl acyllithium species can be stereo-selectively converted to (E) lithium enolates that undergo addition to aldehydes to give /3-hydroxy acylsilanes (Scheme 14). 

A viable iron carbonyl-mediated reduction process converts acid chlorides and bromoalkanes into aldehydes [3, 6]. Yields are high, with the exception of nitro-benzoyl chloride, and the procedure is generally applicable for the synthesis of alkyl, aryl and a,(i-unsaturated aldehydes from the acid chlorides. The reduction proceeds via the initial formation of the acyl iron complex, followed by hydride transfer and extrusion of the aldehyde (cf. Chapter 8). 

Recently proof has been reported for a heterometallic bimolecular formation of aldehyde from a manganese hydride and acylrhodium species [2], Phosphine free, rhodium carbonyl species show the same kinetics as the cobalt system, i.e. the hydrogenolysis of the acyl-metal bond is rate-determining. Addition of hydridomanganese pentacarbonyl led to an increase of the rate of the hydroformylation reaction. The second termination reaction that takes place according to the kinetics under the reaction conditions (10-60 bar, 25 °C) is reaction (3). The direct reaction with H2 takes place as well, but it is slower on a molar basis than the manganese hydride reaction. 

The formation of chiral alcohols from carbonyl compounds has been fairly widely studied by reactions of aldehydes or ketones with organometallic reagents in the presence of chiral ligands. Mukaiyama et al. 1081 obtained excellent results (up to 94% e.e.) in at least stoichiometric addition of the chiral auxiliary to the carbonyl substrate and the organometallic reagent. 

Functionalized zinc carbenoids have been prepared from carbonyl compounds by an indirect strategy. The deoxygenation of a carbonyl compound to an organozinc carbenoid can be induced by a reaction with zinc and TMSCl. Therefore, the aldehyde or ketone, when treated with TMSCl or l,2-bis(chlorodimethylsilyl)ethane in the presence of an alkene, generates the cyclopropanation product. This method is quite effective for the production of alkoxy-substituted cyclopropane derivatives. A 55% yield of the... 

Regeneration of carbonyl compounds from certain derivatives. Ketones can be recovered in satisfactory yield from the phenylhydrazones, p-nitrophenyl-hydrazones, tosylhydrazoncs, oximes, and semicarhazones by reaction with 1 equivalent of (C6H,Se0)20. 2,4-Dinilrophenylhydrazones and N,N-dimethyl-hydrazones arc inert under even rather vigorous conditions. The reagent can also be used to regenerate aldehydes from oximes or tosylhydrazones. 

No cross ozonide was formed from unsymmetrical alkenes. The authors theorized628 that the carbonyl oxide zwitterionic species formed on wet silica gel immediately adds water followed by rapid decomposition of the intermediate hydroxyalkyl hydroperoxide to carboxylic acid and water. It means that water on silica gel acts as participating solvent. In the absence of adsorbed water, rapid recombination of the adsorbed aldehyde and carbonyl oxide due to a favorable proximity effect gives normal ozonide. The low mobility of adsorbed species on the silica surface accounts for the absence of cross ozonides. 

Section 15.2 Alcohols can be prepared from carbonyl compounds by reduction of aldehydes and ketones. See Table 15.3. 

To demonstrate that optically active aldehydes from formylation of the methyl groups of optically active olefins can be obtained as main reaction products with good optical yields, we have studied the hydroformylation of ( + )(S)-2,2,5-trimethyl-3-heptene. None of the methyl groups of the tertiary butyl group were carbonylated. Primarily the reaction product was from carbonylation of the other two methyl groups present in the molecule (Table 1). (S)-3-Ethyl-6,6-dimethylheptanal... 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

Apart from the Takai method and titanium reagents such as 15, silyl reagents 16 and 17 frequently find application in the synthesis of vinylic silanes from carbonyl compounds. Reagent 16 can be utilized with aldehydes and non-enolizable ketones in a reaction analogous to the Peterson olefination Reagent 17 also reacts successfully with enolizable ketones.6... 

Cyanohydrin derivatives have also been widely used as acyl anion synthons. They are prepared from carbonyl compounds by addition of hydrogen cyanide. A very useful variant is to use trimethylsilyl cyanide with an aldehyde to produce a trimethylsilyloxy cyanide. The cyano group acidifies the a position (pKA 25) and the a proton can be removed by a strong base. Alkylation of the anion and unmasking of the hydroxy group cause elimination of cyanide and re-formation of the carbonyl group. 

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