2-Heptanone, synthesis

The ketone 2 heptanone has been identified as contnbuting to the odor of a number of dairy products including condensed milk and cheddar cheese Describe a synthesis of 2 heptanone from acetylene and any necessary organic or inorganic reagents... 

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with A -bromosuccinimide from cyolo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - ... 

This reaction sequence is called the acetoacetic ester synthesis. It is a standard procedure for the preparation of ketones from alkyl halides, as the conversion of 1-bromobutane to 2-heptanone illustrates. 

It is often possible to convert an achiral compound to a chiral compound by (1) addition of a chiral group (2) running an asymmetric synthesis, and (3) cleavage of the original chiral group. An example is conversion of the achiral 2-pentanone to the chiral 4-methyl-3-heptanone (50). In this case, >99% of the product was the (5) enantiomer. Compound 49 is called a chiral auxiliary because it is used to induce asymmetry and then is removed. 

Carbonyl alkylation and condensation reactions are always of great value in synthesis, and the formation of o-ANIS ALDEHYDE via 4,4-dimethyl-2-oxazoline, 2,2-DIMETHYL-3-PHENYLPROPION-ALDEHYDE via alkylation of the magnesio-enamine salt and threo-4-HYDROXY-3-PHENYL-2-HEPTANONE via a directed aldol... 

Acetoacetic ester synthesis is the preparation of substituted acetones, and it s an important method for creating a variety of products. It begins with the reaction of acetoacetic ester (a dicarbonyl) or a similar compound with a strong base to produce a carbanion, which then reacts with alkyl halide, RX. The structure of acetoacetic ester is in Figure 15-10. Figure 15-11 illustrates an example of an acetoacetic ester synthesis and two possible outcomes. Figure 15-12 shows the preparation of 2-heptanone with a 65 percent yield via the acetoacetic ester synthesis. Figure 15-13 presents the preparation of 2-benzylcyclohexanone with a 77 percent yield. 

Examples of this approach to the synthesis of ketones and carboxylic acids are presented in Scheme 1.6. In these procedures, an ester group is removed by hydrolysis and decarboxylation after the alkylation step. The malonate and acetoacetate carbanions are the synthetic equivalents of the simpler carbanions lacking the ester substituents. In the preparation of 2-heptanone (entries 1, Schemes 1.5 and 1.6), for example, ethyl acetoacetate functions as the synthetic equivalent of acetone. It is also possible to use the dilithium derivative of acetoacetic acid as the synthetic equivalent of acetone enolate.29 In this case, the hydrolysis step is unnecessary, and decarboxylation can be done directly on the alkylation product. 

In an analogous synthesis,23 3-butyI-l-heptyne was also characterized by mercuric oxide-sulfuric acid hydration4 to the known 3-butyl-2-heptanone,5 6 which also formed the known semicar-bazone.6... 

The application of this reaction to other ring systems has shown that the yield of the bicyclic hydrocarbon decreases as the strain involved in the product increases. For example, the mercury sensitized decomposition of bicyclo [3.2.0] heptanone-3 (XXIII) leads to very little of bicyclo [2.2.0] hexane and gives more of bicyclo [2.1.1] hexane than of bicyclo [2.2.0] hexane. The reaction has been successfully applied to the synthesis of a substituted bicyclo [2.1.0] pentane (XXVIII) from a sub-... 

Wenkert and coworkers have reported several applications of this chemistry to the synthesis of alkaloids and terpenes.110 A recent example, leading to die methyl ether of tetrahydropyrethrolone (97), is illustrated in Scheme 19.116 Reaction of 1,2-dimethoxypropene with 1 -diazo-2-heptanone (98) resulted in the formation of the labile cyclopropane (99), which was directly converted to the 1,4-diketone (100). Base-induced aldol condensation of (100) readily formed (97). Stereoselective syntheses of prostaglandins1 17 and dicranenone A118 have also been developed using acid-induced ring-opening reactions. 

Bohman B, Unelius CR (2009) Synthesis of all four stereoisomers of 5-hydroxy-4-methyl-3-heptanone using plants and oyster mushrooms. Tetrahedron 65 8697-8701... 

Let s try a synthesis. Suppose we are asked to synthesize 2-heptanone from ethyne. 

Show a synthesis of 2-heptanone using the acetoacetic or malonic ester synthesis ... 

A stereoselective synthesis of 3-( 1,2,4-triazolo[4,3-A ]azin-3-yl)-bicyclo[2.2.1 ]heptanones 58 starting from (l/ )-(+)camphor 56 has been described. The reaction comprises oxidative cyclization of the intermediate hydrazones 57 with methanolic bromine <02TA821>. 

Addition, of potassium cyanide to diethyl benzalmalonate, 30, 84 of sodium bisulfite, to cyclo-heptanone, 34, 25 to phenanthrenequmone, 34, 76 Adipyl azide, 36, 70 Adipyl hydrazide, 36, 69 Alanine, 33, 1 Aldehjde collidine, 30, 42 Aldehydes, stabilization against autoxidation, 37, 40 Aldehyde synthesis, 31, 92... 

N-alkylation of 189 with either l-bromo-2-tetrahydropyranyloxyheptane or l-bromo-2-heptanone was not suited for the further synthesis. 

Asymmetric a-alkylatlon of ketones (7, 10-11 8, 16-17). Enders and Eichenauer have now obtained almost complete asymmetric a-alkylation of acyclic ketones by way of hydrazones formed with 1. An example is the synthesis of (+)-(S)-4-methyl-3-heptanone (4), an ant alarm pheromone, from diethyl ketone. The hydrazone 2 was metalated and alkylated with n-propyl iodide in ether to give 3. 

Heptanone has only one alkyl group bonded to the a carbon, so only one alkyl halide is needed in the acetoacetic ester synthesis. 

Enol acetylation (I, 1174 1178). As a Grst step in the synthesis of 3-n-butyl-2,4-pentanedione, a mixture of 28.6 g. (0.25 mole) of 2-heptanone, 51.0 g. (0.50 mole) of acetic anhydride, and 1.9 g. (0.01 mole) of p-toluenesulfonic acid monohydrate contained in a stoppered 500-ml. round-bottomed flask equipped with a magnetic stirrer is stirred at room temperature for 30 min. Then 55 g. (0.43 mole) of the I 1 boron trifluoridc-acetic acid complex [Reagents, I, 69 (1967)] is added some heat is evolved... 

Yamamoto and Maruoka found that organoaluminum amides are highly effective in the Fischer indole synthesis. In particular, DATMP is the reagent of choice for regioselective Fischer indole synthesis [120]. For instance, treatment of the E)-N-methyl-A-phenylhydrazone of 5-methyl-3-heptanone (123) with DATMP affords 3- ec-butyl-2-ethyl-l-methylindole (125) as the sole isolable product its (Z) isomer gives l,3-dimethyl-2-(2-methylbutyl)indole (124) with high regioselectivity under similar reaction conditions, as illustrated in Sch. 84. 

Probkm 28.28 Using 9-BBN plus any alkenes and unhalogenated acids or ketones, outline all steps in the synthesis of (a) 2-heptanone (b) 4-methylpentanoic acid (c) 4-methyl-2-hexanone (d) l-cyclohexyl-2-propanone (e) ethyl (trans Z-methylcyclopentyl)acetate (f) l>phenyl-4-methyM-pentanone (g) i-cyclopentyl-33 dimethyl-2-butaBone. 

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