Ketone carbohydrate-based

When a sucrose- or other simple carbohydrate-based solution is mixed with yeast and oxygen in a fermenter, carbon dioxide vapour and alcohol are produced. The carbon dioxide can then be passed through a separator to remove any trace cany-over of foam. Once the foam has been removed the carbon dioxide is compressed. It is then scrubbed with water in a packed tower, removing water-soluble impurities such as alcohol, ketones and other aroma chemicals produced during fermentation. 

Simplesse 100 and 300 exhibited some fat-like interactions with saturated aliphatic aldehydes C6-C10 (hexanal, heptanal, octanal, nonanal, decanal), while carbohydrate-based and mixed-blend replacers showed no interaction (Fig. 5.26 and 5.27). Little or no interaction was noted between any of the fat replacers and the saturated aliphatic methyl ketones (Fig. 5.26 and 5.27). Unsaturated carbonyls showed more interactions with protein-based than with carbohydrate-based and mixed-blend replacers (Fig. 5.26 and 5.27). Of the sulfur components studied, propanethiol substantially interacted with Simplesse 100 and 300 (Fig. 5.26). Of these two protein-based replacers, Simplesse 100 showed some fat-like interaction with limonene (Fig. 5.27) and with the two esters ethyl caproate and ethyl heptanoate (Fig. 5.28). 

One of the most common examples of such a sequence is reductive amination of aldehydes or ketones, followed by acylation of the newly formed secondary amine (Scheme 3.6, see [26, 30, 31]). Such a sequence was also applied in the synthesis of carbohydrate-based libraries [110]. The carbonyl compounds were formed by reacting protected 1-thiol-carbohydrates with an a-halo or a,(3-unsaturated ketone. 

Dondoni and co-workers also prepared unsymmetrical carbohydrate-based 1,4-dihydropyridines using a two component Hantzsch synthesis. Treatment of unsaturated ketone 243 with P-aminocrotonate derivative 244 in DMF at 100 C for 48 h gave the corresponding 1,4-dihydropyridine derivative 245 in 61% with only 30% diastereoselectivity. Ribose and mannose analogs were also prepared in 71% and 66% yields, respectively (not shown). A similar diastereoselectivity of 20% was observed when the ribose based P-aminocrotonate was employed. However, no enantioselectivity was obtained with mannose. 

Scheme 3.7 Selected examples of carbohydrate-based and related ketones.

Other eutectic mixtures apart from ChCl-based DESs have been used as reaction media in organic synthesis. In this sense, sweet deep eutectic solvents (also ealled low melting mixtures) based on carbohydrates (i.e., maltose) have been applied as green and biorenewable solvent in the high-yield synthesis of quinazoline derivatives via one-pot three-component coupling of 2-aminoaryl ketones, aldehydes and ammonium aeetate (see Scheme 20.3.3). However, the use of these carbohydrate-based DESs is limited because i) they present relatively high melting points, and ii) their components are rather reactive. 

Phenylhydrazine on exposure to light slowly darkens and eventually becomes deep red in colour salts of the base share this property but to a lesser degree, the sulphate and acetate (of the common salts) being most stable to light. Phenylhydrazine is largely used in organic chemistry to characterise aldehydes and ketones as their phenyl-hydrazones (pp. 342, 345), and carbohydrates as their osazones (pp. 136-140). It is readily reduced thus in the process of osazone formation some of the phenylhydrazine is reduced to aniline and ammonia. On the... 

Cleavage reactions of carbohydrates also occur on treatment with aqueous base for prolonged periods as a consequence of base catalyzed retro aldol reactions As pointed out m Section 18 9 aldol addition is a reversible process and (3 hydroxy carbonyl com pounds can be cleaved to an enolate and either an aldehyde or a ketone... 

Alditol (Section 25 18) The polyol obtained on reduction of the carbonyl group of a carbohydrate Aldol addition (Section 18 9) Nucleophilic addition of an aldehyde or ketone enolate to the carbonyl group of an aide hyde or a ketone The most typical case involves two mole cules of an aldehyde and is usually catalyzed by bases... 

Me3Si)2NH, Me3SiCl, Pyr, 20°, 5 min, 100% yield. ROH is a carbohydrate. Hexamethyldisilazane (HMDS) is one of the most common silylat-ing agents and readily silylates alcohols, acids, amines, thiols, phenols, hydroxamic acids, amides, thioamides, sulfonamides, phosphoric amides, phosphites, hydrazines, and enolizable ketones. It works best in the presence of a catalyst such as X-NH-Y, where at least one of the groups X or Y is electron withdrawing." Yttrium-based Lewis acids also serve as catalysts. ... 

Although Edson2298 postulates that carbohydrates, as well as their derivatives are antiketogenic and compete with fatty acids for oxygen in the liver (as demonstrated by the Warburg technic), his results are only inferential since they are not based on the direct determination of the fatty acid decrease. Bobbitt and Deuel,82 on the other hand, found that not only was the formation of ketone bodies depressed when glycogen was added to the medium, but also that the disappearance of butyrate, as determined by direct analysis, was increased under such circumstances. 

Chiral Ketone from Carbohydrate. Tu et al.100 reported a dioxir-ane-mediated asymmetric epoxidation based on the ketones derived from the low cost material D-fructose (Scheme 4-47). 

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