The IPB has once again been recognized for its exemplary actions in terms of equal opportunity-oriented personnel and organizational policies and has received the TOTAL E-QUALITY certification for the…
The Plant Science Student Conference (PSSC) has been organised by students from the two Leibniz institutes, IPK and IPB, every year for the last 20 years. In this interview, Christina Wäsch (IPK) and…
Kolbe, A.; Porzel, A.; Schmidt, J.; Adam, G.;A new synthesis of [26,28-2H6]brassinolide and [26,28-2H6]castasterone via an unusual methyl migrationJ. Label. Compd. Rad.46231-242(2003)DOI: 10.1002/jlcr.662
Deuterium‐labelled brassinosteroids, namely [26,28‐2H6]castasterone, 8 , and [26,28‐2H6]brassinolide, 9 , were synthesized starting from 6,6‐ ethylenedioxy‐20‐formyl‐2α,3α‐isopropylidenedioxy‐5α‐pregnane, 1 , and 3‐[2H3]methyl‐but‐1‐yne‐[4,4,4‐2H3], 11 . Upon alkylating cleavage of the epoxide 6 with trimethylaluminium‐n‐butyllithium an unusual migration of a neighbouring [2H3]methyl group takes place to afford deuteriation at positions 26 and 28.
Publications
Braga, A. L.; Rubim, R. M.; Schrekker, H. S.; Wessjohann, L. A.; de Bolster, M. W.; Zeni, G.; Sehnem, J. A.;The facile synthesis of chiral oxazoline catalysts for the diethylzinc addition to aldehydesTetrahedron: Asymmetry143291-3295(2003)DOI: 10.1016/j.tetasy.2003.08.029
A range of chiral 4-(1′-hydroxyalkyl)oxazoline catalysts can be obtained in a straightforward two step synthesis, starting from β-hydroxy amino acids like l-serine or l-threonine. Catalyst 4c forms a complex with diethylzinc, effective for the enantioselective addition to aldehydes resulting in high yields and enantiomeric excesses up to >99% even with aliphatic aldehydes. In the latter case the enantiomeric excess showed a marked dependence of the aldehyde's chain length.