2-Butanone synthesis from acetone

Hydroxybenzaldehyde has an agreeable aromatic odor, but is not itself a fragrance. It is, however, a useful intermediate in the synthesis of fragrances. The methyl ether of -hydroxybenzaldehyde, ie, -anisaldehyde, is a commercially important fragrance. Anisaldehyde can be made in a simple one-step synthesis from hydroxybenzaldehyde and methyl chloride. Another important fragrance, 4-(p-hydroxyphenyl)butanone, commonly referred to as raspberry ketone, can be prepared from the reaction of -hydroxybenzaldehyde and acetone, followed by reduction (see Flavors and spices). 

The acetoacetic ester synthesis and direct enolate alkylation are two different methods that prepare similar ketones. 2-Butanone, for example, can be synthesized from acetone by direct enolate alkylation with CH3I (Method [1]), or by alkylation of ethyl acetoacetate followed by hydrolysis and decarboxylation (Method [2]). 

The use of bifunctional catalyst 60d (10 mol%) has permitted the synthesis of several 3-alkyl-3-hydroindolin-2-ones (73) by reaction of acetone (13.6 equiv.) or butanone with a variety of isatins 72 (Scheme 4.22). The addition of acetic acid (20 mol%) as co-catalyst was required to achieve good results. For the case of the reaction with butanone, the process was highly regioselective affording mainly product 73d and 73e. Convolutamydine A, an alkaloid isolated from floridian marine bryozoan Amathia convolute, was prepared by reaction of acetone (3a) with 4,6-dibromoisatin (R =4,6-Brj and =H in 72) catalyzed by compound 60d under similar conditions, with product of type 73 being isolated in practical quantitative yield and 60% ee [134]. 

Zeolites can promote the cyclisation of ketone phenylhydrazones [43]. The phenylhydrazones of acetone and cyclohexanone cyclise in good yields to methylindole and tetrahydrocarbazole, respectively, in the presence of CaX zeolite. Zeolite beta is a highly selective catalyst for the synthesis of 2-benzyl-3-methylindole from phenylhydrazine and l-phenyl-2-butanone (e.g. equation 4.5) [44]. Clays have been reported to promote the ring closure of phenylhydrazones in a similar way [45]. Montmorillonite clay catalyses the ring closure of iV-benzylidene anilines with vinyl ethers to yield tetrahydroquinolines and azetidine derivatives [46]. 

Aldol condensation of citral with acetone followed by acid cyclization gives a mixture of ionones, of which the a-isomer is widely used for its violet odor (Fig. 10.1.9). However, the yff-ionone is more important because it is used in the synthesis of vitamin A. In a similar fashion, pseudoionone can be used in the synthesis of vitamin E. Condensation of citral with 2-butanone gives methylionones, also valued as perfume ingredients. The dihydropseudoionone geranyl acetone, a perfumery chemical having a magnolia-like odor, can be prepared from either geranyl chloride or linalool. 

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