Lactones aldehydes

The photo [2 + 2] reaction between 5-methyl-2,3-dihydro-3-furanone (80) and methyl P-acetoxyacrylate (81) afforded a mixture of four adducts, from which the lactone (82) was isolated. The lactone (82) was reduced to the alcohol (53), which would rearrange quantitatively to the lactone aldehyde (84) upon treatment with... 

Keywords L-galactono-1,4-lactone, aldehyde, montmorillonite, microwave irradiation, acetals... 

Allylic alcohols from sulfones.1 Polish chemists have extended the Julia synthesis of alkenes (11, 474) to a synthesis of allylic alcohols. In the presence of 1 equiv. of BF3 etherate, a-alkoxy aldehydes react with lithiafed sulfones to form adducts that are converted to allylic alcohols on reduction with sodium amalgam. This reaction was developed specifically for a synthesis of prostaglandins from Corey s lactone-aldehyde, but should have wider application. 

Two different modes of reaction have been reported for steroidal A -3-ketones 20). Potassium persulphate in sulphuric acid gave the 4 0xa"3 ketone (23), considered to arise by an initial Baeyer-Villiger oxidation to the unsaturated lactone (21) as an enol lactone of the C(g)-aldehyde (22) this could suffer further degradation through a second Baeyer-Villiger attack on the aldehyde group [64], Other. workers [6 ] used peroxytrifluoroacetic acid and obtained the 5a-carboxy--4"Oxa 3-ketone (25) and the bridged product (26), apparently derived by an internal aldol condensation of the intermediate lactone-aldehyde (24). 

The composition of milkfat is somewhat complex. Although dominated by triglycerides, which constitute some 98% of milkfat (with small amounts of diglycerides, monoglycerides, and free fatty acids), various other lipid classes are also present in measurable amounts. It is estimated that about 500 separate fatty acids have been detected in milk lipids it is probable that additional fatty acids remain to be identified. Of these, about 20 are major components the remainder are minor and occur in small or trace quantities (4, 5). The other components include phospholipids, cerebrosides, and sterols (cholesterol and cholesterol esters). Small amounts of fat-soluble vitamins (mainly A, D, and E), antioxidants (tocopherol), pigments (carotene), and flavor components (lactones, aldehydes, and ketones) are also present. 

Note The frequencies given for the C=0 stretching vibrations for anhydrides, acid chlorides, esters, lactones, aldehydes, ketones, carboxylic acids and amides refer to the open chain or unstrained functional group in a nonconjugated system. If the carbonyl group is conjugated with a double bond or an aromatic ring, the frequency is 30 cm less. If it is... 

Y-nonyl lactone. (aldehyde C-18 4-hydroxy-nonanoic acid, y-lactone y-nonalactone). CH3(CH2)4CHCH2CH2C(0)0. 

The flavor and aroma of many foodstuffs are formed as a result of the action of enzymes and microorganisms. This knowledge can be exploited to obtain both complex flavor mixtures and individual flavor compounds via microbial fermentation and/or enzyme technology. Many different classes of compound can be obtained this way including esters, lactones, aldehydes, ketones and acids. 

Most of them are esters. They may also be alcohols, carboxylic acids, lactones, aldehydes, ketones, and hydrocarbons (Silverstein, 1984). Crucial properties of releaser pheromones are their volatility, their stability, and, of course, the degree of specificity possible to build into a relatively small molecule. The molecular weight tends to be between 80 and 300. On the basis of evaporation and diffusion rates, it can be predicted that long-distance sex pheromones would have a molecular weight between 200 and 300. A pheromone may be one chemical, but usually it is a mixture of chemicals, each of which is a component of the pheromone. Mixtures increase the specificity, a property important especially for the sex pheromones. 

The lipid fraction of milk is dominated by triacylglycerols (TAG), with small amounts of various other lipid classes (Table 13.1). Milk lipids also contain small quantities of glycolipids, fat-soluble vitamins, ether lipids, and flavor components, mainly lactones, aldehydes, and ketones. 

The synthesis of these compounds was relatively straightforward, the 16- and 17- substituted compounds being prepared by reaction of the appropriate Wittig type reagent with Corey lactone aldehyde intermediates of type 1 and the C-15 methyl compounds via a Grignard reaction of an appropriate ketone. 

In general, the position of the second overtone of the carbonyl of simple noncycUc aliphatic compounds shifts to lower wavelength in the series acid chlorides, anhydrides, carboxylic acid monomer, lactones, aldehydes, ketones, and esters. Amide carbonyl second overtones are overwhelmed by bands that involve NH stretch and cannot therefore be included in this comparison. An acid chloride second overtone is at 5400 cm" (1850 nm), propionaldehyde is at 5KX) cm (1960 nm), acetone is at 5100 cm (1960 nm) (with an additional split band at 5260 cm [1900 nm]), and ethyl acetate is at 5160 cm (1940 nm). 

Pietruszka [75] reported the total synthesis of a series of solandelactones (A-H) by the coupling reaction of the lactone 78, the key intermediate, with side chains 79 and 80 (Scheme 5.27). Lactone 78 was prepared by cyclization of the seco-acid 77 under Yamaguchi conditions in good yield (85%). Finally, the Nozaki-Hiyama-Kishi coupling of the unsaturated lactone aldehyde or its saturated counterpart with the iodide 79 or 80 afforded solandelactones A-H in good yields as separable diastereomeric mixtures (ratio 2 1). 

Pineapple Ananas comosus, Bromeliaceae) aroma consists of about 200 alcohols, esters, lactones, aldehydes, ketones, monoterpenes, sesquiterpenes and other volatiles. About 80% of the total volatile substances are esters. The main components in the green fruit are ethyl acetate, ethyl 3-(methylthio)propionate (8-189) with a distinctive pineapple aroma and ethyl 3-(acetoxy)hexanoate (8-190). The ripe fruit contains, as the main esters, ethyl acetate, (2J ,3i )-butane-2,3-diol diacetate (8-191) and ketone 3-hydroxy-butan-2-one. An important compound for the typical character of pineapple aroma, as in strawberry aroma, is 2,5-dimethyl-4-hydroxy-2//-furan-3-one (furaneol), present as a glycoside, and 2,5-dimethyl-4-methoxy-2H-furan-3-one. 

All cross-coupHng approaches on the sulfonate ester Hnker have been tested for various substrates boimd to the polymer, proving that the methodology is compatible with several aromatic systems containing ketones, pyridines, lactones, aldehydes and fluoro-substituents. 

Kitching and co-workers " " developed total syntheses of plakortones C, D, E, and F. Acquisition of plakortone D, the most effective activator of SR-Ca " -pumping ATPase, used stereodefined lactone cores that resulted from asymmetric dihydroxylation of protected homoallylic alcohol 67 (Scheme 15.18). A derived lactone aldehyde was then coupled with an independently generated, sulfone activated side chain unit 68. The 5,6- -double bond, carried through the sequence as a protected, stereodefined diol, was released there by stereospecific sy/j-elimination via an orthoester derivative. Racemic plakortone E was also acquired by using the Pd(II) induced sequence, but in this case, the required, complete acyclic system 69 was assembled first. 

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