Stereoselectivity of the Beckmann Rearrangement of the Oxime Derived from 4-Bromoacetophenone

The Beckmann rearrangement involves the conversion of an oxime into an amide through treatment with various Brønsted or Lewis acids. This reaction entails the migration of an alkyl group to the nitrogen center, which is electron-deficient. Valuable insight into this mechanism arises from the observation that the migrating alkyl group is positioned opposite to the oxime's hydroxyl group. This outcome is clarified by proposing that the migration of the alkyl group occurs in concert with the heterolytic breaking of the N-O bond. The resultant nitrilium ion is subsequently neutralized by the addition of a nucleophile, often water. Subsequent tautomerization yields the amide product, as depicted in the provided scheme.

Regrettably, instances of stereospecific Beckmann rearrangements are infrequent, as oximes tend to be stereochemically unstable under the reaction conditions. Frequently, prior conversion between (E)-and (Z)-oxime is prompted by the acidic conditions required for the rearrangement. Consequently, any stereochemical particulars are forfeited. Illustrated in the subsequent example, the initial oxime not only forms with notable stereoselectivity, but the ensuing rearrangement also cleanly results in a single amide product. This outcome allows for the determination of the initial oxime's stereochemistry. The assessment of the amide is performed by recognizing the products obtained following hydrolysis.

Related Products of 4-Bromobenzoic Acid :

Related Products of 4-Bromoaniline:

A102916115843-99-798%

4-Bromo-3-chloro-2-fluoroaniline

A783551429683-46-598%

4-Bromo-2-fluoro-6-methylaniline

A157310157026-19-297+%

5-Bromo-3-(trifluoromethyl)benzene-1,2-diamine

A291903348169-39-198%

4-Bromo-2-methoxy-6-methylaniline

A2395121940-27-897%

4-Bromo-2,5-dichloroaniline

A975210116369-25-696%

4-Bromo-3-(trifluoromethoxy)aniline

A545553157590-60-898%

4-Bromo-5-(trifluoromethyl)benzene-1,2-diamine

A986548950759-54-395%

(E)-Ethyl 3-(2-amino-5-bromophenyl)acrylate

A93380330273-22-498%

4-Bromo-2-ethylaniline hydrochloride

A391861113571-15-698+%

4,6-Dibromo-2,3-dichloroaniline

A24375650739-76-995%

(2-Amino-3,5-dibromophenyl)methanol

A419636854624-54-795%

4-Bromo-3-methyl-2-nitroaniline

A1923931008361-80-598%

4-Bromo-3-chlorobenzene-1,2-diamine

A16463150910-55-997%

2-Amino-3,5-dibromobenzaldehyde

A14792439263-32-695%

2-Amino-5-bromobenzonitrile

A142624827-23-698+%

2,4-Dibromo-6-nitroaniline

A312118737702-63-595%

2-(2-Amino-5-bromophenyl)acetic acid

A560673180624-08-298%

4-Bromo-2-iodo-6-nitroaniline

A285694157026-18-198%

4-Bromo-2-nitro-6-(trifluoromethyl)aniline

A10241384752-20-595%

5-Bromo-3-nitrobenzene-1,2-diamine

A29819219056-40-798%

4-Bromo-3-methoxyaniline

A116850784478-69-397%

4-Bromo-2-fluoro-5-propoxyaniline

A12065335736-52-895%

2,4-Dibromo-5-methoxyaniline

A116462153505-36-395%

4-Bromo-5-fluoro-2-nitroaniline

A10351653324-38-298%

4-Bromo-3-nitroaniline

A164568139253-79-598%

2-Amino-5-bromo-N,N-dimethylbenzamide

A3213471257535-31-197%

4-Bromo-2-nitro-6-(trifluoromethoxy)aniline

A265764116369-24-598%

4-Bromo-5-chloro-2-fluoroaniline

A52211480058-84-098%

4-Bromo-2,6-diisopropylaniline

A57588687547-06-698%

4-Bromo-2-fluoro-5-nitroaniline

A347689885266-98-897%

4-Bromo-2-chloro-6-(trifluoromethoxy)aniline

A222374330794-03-195%

4-Bromo-5-fluoro-2-methoxyaniline

A50459213445-89-195%

1-(2-Amino-3,5-dibromophenyl)ethanone

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