Dehydrohalogenation of a-Halo ketones

Dehydrocortisone, 87 8-Dehydroestradiol, 4 9(ll)-dehydroestradioI 3-methyl ether, 2 8(14)-DehydroestradioI 3-methyl ether, 3 Dehydrofluorination, 452 Dehydrofluorination of gem-difluorides, 446 Dehydrogenation, 306 Dehydrohalogenation of a-Halo ketones, 287 16-Dehydropregnenolone, 40 16-Dehydropregnenolone acetate, 48 16-Dehydropregnenolone tetrahydropyranyl ether, 40... 

DehydrohalogenatUm. A preliminary report states that the reagent is useful for the dehydrohalogenation of a-halo ketones under mild conditions. On treatment with the salt in acetone, 4 3-bromocoprostanone afforded cholestenone in good yield. 

Base-induced 1,3-dehydrohalogenation of a-halo ketones 1 leads to cyclopropanones 2, but these reactive species almost always react further with the nucleophiles present to give addition products at the carbonyl group. The resulting adducts may be isolated, but in most cases react further under the influence of base to ring open to carboxylic acid derivatives 3a, b. 

Reaction conditions which usually lead to dehydrohalogenation of a-halo ketones did not give the corresponding cyclobutenone. ... 

There are several general ways to make compounds of this kind the aidol condensation, to make unsaturated aldehydes and ketones dehydrohalogenation of a-halo acids and the Perkin condensation, to make unsaturated acids. Besides these, there are certain methods useful only for making single compounds. 

Pyrolysis of carboxylic acids Dehydrohalogenation of acyl halides Dehalogenation of a-halo acyl halides Rearrangement of diazo ketones (Wolff)... 

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