Anis aldehyde

Each of these approaches may be the best for any given lactone the one in the last frame for example would allow you to use any Michael acceptor and any aldehyde. 

Aldehydes are easily oxidized to carboxylic acids under conditions of ozonide hydroly SIS When one wishes to isolate the aldehyde itself a reducing agent such as zinc is included during the hydrolysis step Zinc reduces the ozonide and reacts with any oxi dants present (excess ozone and hydrogen peroxide) to prevent them from oxidizing any aldehyde formed An alternative more modem technique follows ozone treatment of the alkene m methanol with reduction by dimethyl sulfide (CH3SCH3)... 

Aldehydes can undergo an intermolecular oxidation—reduction (Canni22aro reaction) in the presence of base to produce an alcohol and a carboxyUc acid salt. Any aldehyde is capable of participating in such a reaction, however, it is more common for those containing no protons on the alpha carbon, for example... 

Virtually any aldehyde or ketone and any CH-acidic methylene compound can be employed in the Knoevenagel reaction however the reactivity may be limited due to steric effects. Some reactions may lead to unexpected products from side-reactions or from consecutive reactions of the initially formed Knoevenagel product. 

These results show that chemical yields are generally higher than for most aldol-type additions of ester cnolates. mainly because of the chemical activation of the methylene group by the sulfoxide, which makes this reaction suitable for any aldehyde or ketone. High asymmetric induction is also generally observed. The aldol adducts obtained by addition to aldehydes have been transformed into optically active four- and five-membered lactones38. 

Danshefsky s diene [19] is the 1,3-butadiene with amethoxy group at the 1-position and a trimethylsiloxy group at the 3-position (Scheme 18). This diene and Lewis acids extended the scope of hetereo-Diels-Alder reactions with aldehydes [20], This diene reacts with virtually any aldehyde in the presence of Lewis acids whereas dienes usually react with only selected aldehydes bearing strongly electron accepting a-substituents. There are two (Diels-Alder and Mukaiyama aldol) reaction pathways (Scheme 18) identified for the Lewis acids catalyzed reactions of Danishefsky diene with aldehydes [21, 22]. The two pathways suggest that these reactions occur on the boundary between the delocahzation band (the pericyclic... 

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... 

Like any aldehydes aromatic aldehydes undergo Clemmensen reduction [758, 778] and Wolff-Kizhner reduction [759, 774] and give the corresponding methyl compounds, generally in good yields. The same effect is accomplished by conversion of the aldehydes to p-toluenesulfonyl hydrazones followed by reduction with lithium aluminum hydride (p. 106). 

Any aldehyde other than formaldehyde reacts with a Grignard reagent to produce a secondary alcohol (see Figure 14-5). The general mechanism is the same for any aldehyde (see Figure 14-6). As shown in Figure 14-7, more than one path may lead to the same alcohol. 

Refs Same as above and also J. Troger CEicker, JPraktChem 116, 29(1927) 4,6-Dinitro-(m-anis aldehyde) or 4,6-Dinitro-... 

N itro-(p-anis aldehyde )-pkenylkydrazone, HjCO.QH/NOaJ.CHiN.NH.QHs, is described in Beil 15, 193 [80]... 

Attempts were made to reduce any aldehyde and ketone function with sodium borohydride. A 1.5-gram sample was weighed into a 100-ml. reaction flask and suspended in 10 ml. of methanol. A solution of 0.3 gram of sodium borohydride in 25 ml. of 0.1 IV sodium hydroxide was added to the sample over a period of 15 minutes. The mixture was refluxed under nitrogen for 6 hours, filtered, and washed thoroughly with water. The amount of aldehyde and ketone was estimated by the decrease in the 5.8 micron peak in the infrared spectrum of the treated sample as compared with the untreated sample. 

SAMPLE SOLUTION (a) A good way to correctly identify the aldol addition product of any aldehyde is to work through the process mechanistically. Remember that the first step is enolate formation and that this must involve proton abstraction from the a carbon. 

Most of the alcohol and any aldehyde must be removed by evaporation at room temperature since heating the wet product at once to no° always causes the formation of orange-colored impurities. 

To further purify the alcohol the above product is shaken with finely divided silver oxide. This oxidises any aldehyde present to acetic acid. Caustic soda is added to bind the acid, and the alcohol distilled, using a good column (see p. 22). The portion passing over at constant temperature is then treated with calcium turnings in the same way as methyl alcohol (see above). The anhydrous alcohol is very hygroscopic, and must not be exposed to air. 

Enzymology,29 techniques of isolation, and descriptions of a number of them. Apparently, only three have been considered for preparative chemistry, that is, aldolase, sialyl aldolase, and Kdo synthetase. However, whole cells of some strains of Escherichia coli have been used as sources of fucu-lose 1-phosphate aldolase (E.C. 4.1.2.17) or rhamnulose 1-phosphate aldolase (E.C. 4.1.2.19).30 Extraction, and concentration to a suitable degree of homogeneity, of noncommercially available aldolases are not difficult. The examination of their synthetic possibilities could be very rewarding for we already observe that the wealth of chemicals prepared with the help of aldolase and sialyl aldolase far exceeds what they make in Nature. Still, not any aldehyde, however hydrophilic, is a substrate for aldolases. 

The bisulfite treatment removes any aldehydic material present at this point. Since this ketone is quite inert to sodium bisulfite, the yield is not lowered by this procedure. 

This is generally done during an experimental work up where the products of the reaction are dissolved in a water immiscible organic solvent. Aqueous sodium bisulphite is then added and the mixture is shaken thoroughly in a separating funnel. Once the layers have separated, any aldehydes and methyl ketones will have undergone nucleophilic addition with the bisulphite solution and will be dissolved in the aqueous layer as the water soluble salt. The layers can then be separated. If the aldehydes or methyl... 

As we will see later, the release of acids is characteristic of the breakdown of esters in the presence of water. This acidity, in alcoholic fragrances, can in turn result in the formation of acetals between the ethanol and any aldehydes that may be present in the perfume. Although this reaction is reversible in principle, where there is a large excess of alcohol in the product as opposed to aldehydes, as is usually the case, the aldehydes can be almost entirely lost, with a catastrophic effect on the odor. 

Regioselective reductions of the maleic anhydride derivatives (387) and (389) with lithium aluminum hydride yielded (388) and (390). Metallation of the O-methyltetronic acid (388) with lithium N- cyclohexyl-A- isopropylamide followed by treatment with, for example, p-anis aldehyde led to pulvinones such as (391) (79JCS(Pl)7o). 

---