
TY  - JOUR
A1  - Hudson, CB 
A1  - Robertson, AV 
A1  - Simpson, WRJ 
T1  - On the synthesis of 3,4-dihydroxyprolines. I. <I>cis</I>-Glycolation of 3,4-dehydroproline derivatives
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1968
VL  - 21
IS  - 3
SP  - 769
EP  - 782
KW  - 
UR  - https://doi.org/10.1071/CH9680769 
N2  - The interaction of OsO4 and protected derivatives of 3,4-dehydro-DL-proline gives high yields of 2,3-trans-3,4-cis-3,4-dihydroxy-DL-proline derivatives, with only traces of the 2,3-cis-3,4-cis diastereoisomers. Corresponding &#945;-glycolation with KMnO4 gives mixtures of the 2,3-trans-3,4-cis and 2,3-cis-3,4-cis isomers in the ratio 1 : 1. Separation of the components of such mixtures is extremely difficult. The free amino acids in these two families of the 3,4-dihydroxy-DL-prolines have been characterized. Epimerization at C2 of 2,3-cis derivatives occurs readily. O-Tosylation of the 2,3-cis series occurs more readily than for other hydroxyprolines. Esters of N,O,O-tritosyl-2,3-trans-3,4-cis-3,4-dihydroxyproline are converted very rapidly by mild alkali into the equivalent esters of X-tosylpyrrole-2-carboxylic acid. For the corresponding N,O,O-tritosyl carboxylic acid, decarboxylation also takes place during aromatization, to yield N-tosylpyrrole. 
ER  -

