N-Bromoacetamide-Silver Acetate-Acetic Acid

(MeCONHBr)

[79-15-2]  · C2H4BrNO  · N-Bromoacetamide-Silver Acetate-Acetic Acid  · (MW 137.96) (AgOAc)

[563-63-3]  · C2H3AgO2  · N-Bromoacetamide-Silver Acetate-Acetic Acid  · (MW 166.91) (HOAc)

[64-19-7]  · C2H4O2  · N-Bromoacetamide-Silver Acetate-Acetic Acid  · (MW 60.05)

(cis dihydroxylation of alkenes)

For information on the individual components see N-Bromoacetamide, Silver(I) Acetate and Acetic Acid.

The mixture of N-bromoacetamide (NBA) with silver acetate serves as an extremely useful means of executing cis dihydroxylation of alkenes from the more hindered face, via the corresponding 1,2-diacetoxyalkane (eq 1).1 In particular, the method offers an improvement over the previous reagents used to carry out most hindered dihydroxylations namely Iodine-Silver Acetate (the so-called Woodward hydroxylation2); under the latter conditions, the reaction represented in eq 1 produces a mixture of diastereoisomers. The use of NBA furnishes a single diol in all reactions of cyclohexenes except where methylcyclohexenes are employed; in the reaction of these substrates a product mixture very similar to that seen under Woodward conditions is obtained (Table 1), but yields of diol are improved.

The NBA-AgOAc mixture is also effective in the hydroxylation of prochiral acyclic alkenes and has been thus employed in studies towards total synthesis of daunosamines (eq 2).3,4 In these studies, reaction of (1) gave the desired L-lyxo stereoisomer in excess; use of Woodward conditions gave this isomer in minor amounts (4:1 xylo:lyxo) while Osmium Tetroxide gave only a slight preponderance of lyxo (1:2 xylo:lyxo).3

Contrary to one report, NBA-AgOAc is not claimed to effect bromoacetoxylation of alkenes.5


1. Jasserand, D.; Girard, J. P.; Rossi, J. C. TL 1976, 1581.
2. Woodward, R. B.; Brutcher, F. V. JACS 1958, 80, 209.
3. Dyong, I.; Wiemann, R. CB 1980, 113, 2666.
4. Dyong, I.; Friege, H.; zu Höne, T. CB 1982, 115, 256.
5. FF 1979, 7, 182.

Joseph Sweeney

University of Bristol, UK



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