Miescher mining
The Miescher breakdown , also Meystre-Miescher breakdown , is a name reaction from the field of organic chemistry . The reaction was named after the chemists Charles Meystre and Karl Miescher (1892–1974) and serves to break down the side chain of bile acids .
Overview reaction
The Miescher degradation is a multi-stage reaction chain for the degradation of the side chain of bile acids 1 with the formation of special ketones 2 :
Reaction sequence
The following course of the reaction is described in the literature:
In the first step, phenylmagnesium bromide reacts with the ester function in the bile acid side chain 1 in a Grignard reaction . In an acid-catalyzed elimination reaction , water is split off with the formation of a C = C double bond. It is then brominated in the allyl position with N- bromo succinimide (NBS) . A conjugated diene is then formed in a base-catalyzed elimination reaction . The diene is oxidized with chromium trioxide , a methyl ketone 2 is formed .
Individual evidence
- ^ A b Zerong Wang: Comprehensive Organic Name Reactions and Reagents . John Wiley & Sons, Inc., Hoboken, NJ, USA 2010, ISBN 978-0-470-63885-9 , pp. 1940 , doi : 10.1002 / 9780470638859 .
- ↑ Meystre, C .; Frey, H .; Wettstein, A. and Miescher, K., Helv. Chim. Acta, 1944 , 27, 1815-1824, doi: 10.1002 / hlca.194402701230 .
- ↑ A. Wettstein, Ch. Meystre: About steroids. (Part 68). A simple breakdown of the bile acid side chain X 2 ). New partial syntheses of 11-dehydrocorticosterone and 11-keto-progesterone . In: Helvetica Chimica Acta . tape 30 , no. 5 , 1947, pp. 1262-1269 , doi : 10.1002 / hlca.19470300520 .