J. Weiguny, H. Schäfer
Mar 11, 1994
Citations
0
Influential Citations
9
Citations
Journal
European Journal of Organic Chemistry
Abstract
The key intermediate of a novel synthesis of prostaglandin precursors, (1′R,4′S,3R/S)-3-(cis-4-acetoxycyclopent-2-enyl oxy)-3-ethoxypropionic acid (3), is prepared by two different synthetic sequences: In a first strategy transacetalization of ethyl 3,3-diethoxypropionate (6) with (1R, 4S)-4-acetoxy-1-hydroxy-2-cyclopentene (7) leads to the formation of the mixed acetal 8. By subsequent hydrolysis and acylation 8 could be converted into acid 3 in six steps in 6% overall yield. However, the generation of acid 3 by bromoalkoxidation of 3-ethoxyacrylates 13d, e and subsequent electrochemical reduction proved to be more efficient. In this reduction it is possible to debrominate the α-bromo esters 14d, e and to remove the 2-haloethyl ester group in one step. Using this reaction sequence, we could synthesize acid 3 in five steps in 38% overall yield.