Lactone rearrangement

Acylisoxazol-5-ones (129), which are -diketones, on being heated in alkaline medium undergo acyl-lactonic rearrangement to form stable isoxazole-4-carboxylic acids (130). ... 

Each diastereoisomer of this unsaturated lactone rearranged on heating into a different isomer of a ten-membered cyclic diene. What sort of reaction is this, what kind of isomers are they, and... 

Korte, F., Storiko, K. Acyl-lactone rearrangement. XV. The rearrangement of 4-acyl-5-oxazolones. Chem. Ber. 1960, 93, 1033-1042. 

Oxonium ions from )S-lactones rearrange to ji-oxo esters. 

An acyl-lactone rearrangement has been utilized in synthesizing nicotine (94), myosmine (94), and iV-methylanabasine (95). Ethyl nico-tinate and 1-methyl-2-pyrrolidone treated with potassium in dry ether gave 3-nicotinoyl-l-methyl-2-pyrrolidone (LXIII). LXIII was hydrolyzed with acid to LXIV which on hydrogenation gave dLnicotine. 

Ohno and co-workers envisioned the use of the well-advanced intermediate B5 (Scheme 23) as the common progenitor of both antibiotics. Thus, it was proposed that the derived ketone GII would react with (dichloromethyl)lithium to give Gill, which would be subjected to the y-lactone - 8-lactone rearrangement that had been worked out so well for actinobolin (see Scheme 8). As of this writing, there has been no further report on the progress of this planned strategy. 

Lactones from ethylenecarboxylic acids Isolation of a fast-forming unstable lactone Rearrangement of lactones... 

The synthesis of bis-O-methylpulviquinone-A lactone (135) has been achieved by using successive grevillin-terphenylquinone-pulvinic lactone rearrangements starting from the naphthaldehyde (134) (Scheme 21) (561). 

SCHONBERG, A., and A. Sina Molecular Rearrangements. Part V. A Case of a Thermal Reversible a-Diketone-y-Lactone Rearrangement. Some Experiments with Vulpinic Acid and Related Compounds. J. Chem. Soc. (London) 601 (1946). 

Lactone rearrangement with O-deacetylation Hydrogenation of carbon-carbon double bonds... 

The well-known preparation of 8-lactones by reaction of ketene with carbonyl systems has been modified such that if the reaction is performed on a methyl ketone in the presence of BF3, the initially formed 8-lactone rearranges to a y-lactone l ... 

The acyl lactone rearrangement , namely the conversion of an a-acy 1-6-lactone (i) to the corresponding dihydropyran carboxylic ester (ii) is a facile and convenient process, see F. Korte and K. H. Buchel, Angew. Chem., 71,709 (1959). 

A solii. of ferf-butyl methyl ketone in GGI4 treated with BFs-etherate, ice-cooled, ketene introduced, then the solvent removed in vacuo whereby the intermediate / -lactone rearranges exothermically to the y-lactone y ,, y,y-tetramethyl-y-butyrolactone. Y 67%. F. e. s. G. Metzger, D. Borrmann, and R. Wegler, B. 100,1817 (1967). 

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