カルボン酸から3-ヒドロキシ酸の合成及び3-ヒドロキシ酸, 3, 4-不飽和酸とホルムアルデヒドの反応による種々のラクトン類の合成

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3-Hydroxy acids were synthesised in good yield from ketones and carboxylic acids using lithium naphthalenide in the presence of diethylamine. From cyclohexanone and propionic acid, 2- (1-hydroxy- cyclohexyl) propionic acid (3) was obtained in 98% yield. 3-Hydroxy acids were treated with various acidic reagents to give 3, 4-unsaturated carboxylic acids and γ-butyrolactones. From the reaction of (3) with p-toluenesulphonic acid, 2- (1-cyclohexenyl) propionic acid (4) was obtained (yield 98%) and with 97% sulphuric acid 2- (2-hydroxycyclohexyl) propionic acid lactone (5) was formed (93% yield).<BR>We have found that an 2, 3-unsaturated δ-lactone or spirolactone could be prepared from the reaction of 3-hydroxy acid with 1, 3, 5-trioxane or paraformaldehyde. When a mixture of the compound (3), 1, 3, 5-trioxane, and sulfuric acid was refluxed in acetic acid, 2- (2-hydroxymethylcyclohexylidene) propionic acid lactone (6) was obtained in 88% yield; interestingly, at 25°C, only 2, 5-dimethyl-4, 6-dioxa-3-oxo spirobicyclohexane (7) was obtained in 71% yield.<BR>3, 4-Unsaturated acids were condensed with paraformaldehyde in boiling acetic acid containing a small amount of aluminium chloride to afford 2, 3-unsaturated δ-lactones. From 2- (1-cyclohexenyl) octanoic acid (8) and paraformaldehyde, 2- (2-hydroxylmethylcyclohexylidene) octanoic acid lactone (9) was obtained in up to 93% yield.
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