- Organocatalytic asymmetric 5-hydroxypyrrolidine synthesis: a highly enantioselective route to 3-substituted proline derivatives
-
The highly enantioselective organocatalytic tandem reaction between 2-acylaminomalonates and α,β-unsaturated aldehydes is presented. The reaction is a direct entry to 5-hydroxypyrrolidines and 3-substituted proline derivatives, which are furnished in high
- Rios, Ramon,Ibrahem, Ismail,Vesely, Jan,Sundén, Henrik,Córdova, Armando
-
p. 8695 - 8699
(2008/03/14)
-
- Synthesis of Enantio- and Diastereoiso-merically Pure Substituted Prolines via Condensation of Glycine with Olefins Activated by a Carbonyl Group
-
The glycine fragment in the nickel(II) complex (1) formed from the Schiff's base of glycine and (S)-o-benzophenone (2) undergoes base-catalysed Michael addition to acrylaldehyde, α-methylacrylaldehyde, (E)-crotonaldehyde, (E)-cinnamaldehyde, and methyl vinyl ketone.No products of 1,2-addition were found in the Et3N-catalysed reactions.Addition followed by epimerization of the isomeric complexes proceeds with high diastereoselectivity at Cα (90percent) and Cβ of the corresponding amino acid side chains.After chromatographic separation, the diastereoisomerically pure complexes were decomposed and the resulting dihydropyrrole-2-carboxylic acids reduced with NaBH3CN to give (S)-proline, trans-3-methyl-(S)-proline, trans-5-phenyl-(S)-proline, and a mixture of cis- and trans-5-methyl-(S)-prolines.The chiral auxiliary (2) was recovered in 80-90percent yield.
- Belokon', Yuri N.,Bulychev, Aleksandr G.,Pavlov, Viacheslav A.,Fedorova, Eugenia B.,Tsyryapkin, Vladimir A.,et al.
-
p. 2075 - 2084
(2007/10/02)
-