Ketone preparation

By catalytic reduction of a p-unsaturated ketones, prepared from aldehydes by the Claisen - Schmidt reaction (see under Aromatic Aldehydes), for example ... 

Sodium suifite, acid (saturated) dissolve 600 g of NaHS03 in water and dilute to 1 liter for the preparation of addition compounds with aldehydes and ketones prepare a saturated solution of sodium carbonate in water and saturate with sulfur dioxide. 

This method may be used for the preparation of larger quantities, a batch twenty times this size giving a yield of 87 per cent. It may be used also for the preparation of other aromatic acids where suitable ketones are available. Methyl a-naphthyl ketone prepared by Caille s method is not suitable for the preparation of a-naphthoic acid as it contains at least 30 per cent of the methyl d-naphthyl ketone. 

Steroidal A -dienamines are formed with a high degree of selectivity in the presence of 17- or 20-ketones. Preparation of morpholine and pyrrolidine enamines is achieved by azeotropic removal of water with or without a catalyst. Pyrrolidine enamines are also formed efficiently by addition of the base to the hot solution of the ketone in methanol followed by immediate cooling. ... 

Grignard additions to conjugated ketones preparation of la-methyl-17,20 20,21-bismethylenedioxypregna-4,6-diene-... 

Morpholine enamine of methyl isopropyl ketone prepared by this method was found to be a 3 7 mixture of di- and tetrasubstituted isomers (126 and 127). 

Piperitone can be most easily obtained from the higher boiling portions of the oil of E. dives. It combines slowly with sodium-bisulphite, and by repeated agitation for two or three weeks eventually forms crystals in some quantity. A proportion of alcohol assists the combination. The pure ketone prepared from the purified crystals is colourless at first, but on long standing becomes slightly yellowish in tint. It has a burning peppermint-like taste and odour. The formula is... 

Givaudan Co., however, compare the properties of piperitone with those of the ketone prepared synthetically by Wallach, and discovered in Japanese peppermint oil by Schimmel and later in camphor oil by Bchimmel, and finally in the oil of Cymhopogon sennaarensis by Roberts,"... 

FRAGMENTATION OF a,(J-EPOXYKETONES TO ACETYLENIC ALDEHYDES AND KETONES PREPARATION OF 2,3-EPOXYCYCLOHEXANONE AND ITS FRAGMENTATION TO 5-HEXYNAL... 

The less highly substituted Mannich bases can also be prepared directly from ketones and dimethyl(methylene)ammonium trifluoroacetate by the procedure reported here, which takes advantage of the isomerization of Mannich bases in trifluoroacetic acid. (In acetic acid the Mannich bases undergo elimination of dimethylamine to give a-methylene ketones.) This method is rapid and affords products having an isomeric purity of at least 90% without difficult separations. The 49-57% yield of l-(di-methylamino)-4-methyl-3-pentanone obtained with this procedure compares favorably with the overall yields of amino ketones prepared by the indirect routes mentioned previously. 

The trialkylborane can be transformed to a dialkyl(ethoxy)borane by heating with acetaldehyde, which releases the original chiral a-pinene. Finally application of one of the carbonylation procedures outlined in Scheme 9.1 gives a chiral ketone.17 The enantiomeric excess observed for ketones prepared in this way ranges from 60-90%. 

Table 4.2 a,p-Epoxy ketones prepared by epoxidation of ( )-2-alkyliden-l-oxo-l,2,3,4-tetrahydronaphthalenes using diethylzinc and (lR,2R)-V-methylpseudoephedrine[8l... 

Table 4.3 a, P-Epoxy ketones prepared by epoxidation of a-enones using diethylzinc and (1R, 2R)-/V-methylpseudoephedrine (according to the relevant publication)181. 

The ketone catalyst is readily prepared from D-fructose by ketalization and oxidation. The other enantiomer of this ketone, prepared from L-sorbose,... 

Copper-Catalyzed Conjugate Addition of Functionalized Organozinc Reagents to a,p-Unsaturated Ketones Preparation of Ethyl 5-(3-Oxocyclohexyljpentanoate. 

G. Cahiez, S. Marquais, and M. Alami 135 MANGANESE-COPPER-CATALYZED CONJUGATE ADDITION OF ORGANO-MAGNESIUM REAGENTS TO a,(J-ETHYLENIC KETONES PREPARATION OF 2-(1,1 -DIMETHYL-PENTYL)-5-METHYLCYCLO-HEXANONE FROM PULEGONE... 

The a,(3-unsaturated aldehydes or ketones prepared earlier in this chapter are useful as starting materials for a number of reactions. In this section, you investigate some of these reactions. 

Ketones, preparation from carboxylic acid, 66, 119 8-Lactams, 65, 140... 

Addition of organometallic reagent to ketone preparation of tertiary alcohols... 

In the nitrosation of ethyl isopropyl ketone (Preparation 2-4), acetyl chloride is used as a catalyst. While aqueous hydrochloric acid has also been used to catalyze this reaction, anhydrous hydrogen chloride or acetyl chloride evidently is more effective as far as the yield is concerned. To be noted here is that the greater yield is that of the true nitroso compound. However, the secondary carbon atom of the ethyl group is converted into an oxime on nitrosation. 

In the reactions listed in Table 3, Michael addition of a primary aromatic amine to an a, (3-unsaturated aldehyde or ketone (prepared in situ) is followed by cyclization and oxidation of the intermediate dihydroquinoline to a quinoline (138 — 141). 

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