Bromomagnesium Diethylamide

[5856-91-7]  · C4H10BrMgN  · Bromomagnesium Diethylamide  · (MW 176.34)

(aldol condensation; Claisen ester condensation)

Alternate Name: diethylaminomagnesium bromide.

Preparative Method: has been prepared from Ethylmagnesium Bromide and diethylamine in anhydrous ether by mixing at 0 °C, then stirring at rt followed by a 15 min reflux.1,2

Handling, Storage, and Precautions: use in a fume hood.

Although bromomagnesium diethylamide has been shown to be an effective base for the Claisen ester condensation of certain esters, its use is limited by its tendency to react with the ester group to form amides.3,4 The related reagent Bromomagnesium Diisopropylamide does not suffer from this drawback and has been used more frequently.

Diethyl succinate has been successfully condensed with trifluoroacetophenones using bromomagnesium diethylamide (eq 1).5,6

The condensation of (-)-menthyl acetate with alkyl phenyl ketones,1,7 dialkyl ketones,8 or aromatic aldehydes8 gives optically active b-hydroxy esters which can be hydrolyzed to the optically active b-hydroxy acids (eq 2). Synthetic yields are 30-80% and optical yields are 16-60%. As the size of R increases, the optical yield decreases.7

1. Sisido, K.; Kumazawa, K.; Nozaki, H. JACS 1960, 82, 125.
2. Mitsui, S.; Kudo, Y. T 1967, 23, 4271.
3. Hauser, C. R.; Walker, H. G., Jr. JACS 1947, 69, 295.
4. Royals, E. E.; Turpin, D. G. JACS 1954, 76, 5452.
5. Ukerun, S. O. LA 1988, 907.
6. Ukerun, S. O. LA 1989, 687.
7. Dongala, E. B.; Dull, D. L.; Mioskowski, C.; Solladié, G. TL 1973, 4983.
8. Kudo, Y.; Iwasawa, M.; Kobayashi, M.; Senda, Y.; Mitsui, S. TL 1972, 2125.

Ronald H. Erickson

Scios Nova, Baltimore, MD, USA

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