Y-Hydroxycarboxylic acids

However, Forstner et al. (1997a) also point out that the formation of furanones from the cyclization of -y-hydroxycarboxylic acids (e.g., C3H7CH(OH)CH2CH2COOH) in the condensed phase is well known. If -y-hydroxycarboxylic acids are formed from OH reactions with the alkenes, the furanones can be formed from this cyclization in the particles. However, Forstner and co-workers also indicated that such a reaction could occur during sample workup and hence the true yields of the furanones could be significantly smaller. 

Reactions of hydroxycarboxylic acids, HO(CHj) COOH, also depend on value of n. In acid solutions, y-hydroxycarboxylic acid (n = 3) and 8-hydroxycarboxylic acid (n = 4) form cyclic esters (lactones) with, respectively, five-membered and six-membered rings. 

When /8-propiolactone is heated under pressure with anhydrous ammonia, /3-hydroxypropionamide is obtained. A mole of /3-propiolactone (72 g) is heated under pressure with 5.87 moles (100 g) of ammonia for 16 hr at 100 C to obtain a 50 per cent yield of crude /3-hydrox5rpropionamide, which can be purified by vacuum distillation. By a dehydration reaction, the amination of the lactone of a y-hydroxycarboxylic acid yields a stable cyclic amide or lactam, as is the case when y-butyrolactone is converted to a-pyrrolidone. However, owing to the instability of the four-membered ring, a lactam cannot be formed from ammonia and the lactone of a /8-hydroxycarboxylic acid, such as -propiolactone. When hydroxy-propionamide is dehydrated, no lactam is formed. Only unsaturated acid derivatives can be obtained, as shown in the equation below. 

Oxetan-2-ones are more reactive than y- and ( lactones because of ring strain. On treatment with sodium hydroxide, salts of y -hydroxycarboxylic acids are formed owing to attack of hydroxide ions on the C-atom of the carbonyl group. 

Synthesis of carboxylic acids from ketones via y -hydroxycarboxylic acid fcrf-butyl esters Modified Reformatskii synthesis... 

Isopropylmagnesium chloride y -Hydroxycarboxylic acid esters from 0X0 compounds... 

Figure 11.77 Enantioselective reduction of an aryl f CIalkyl ketone using stoichiometric amounts of (+ )-lpc2BCI synthesis of an e.p. substituted y-hydroxycarboxylic acid derivative...

Ketones from y >hydroxycarboxylic acid esters Cation speeifieity... 

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