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…
Gabriel, T.; Wessjohann, L.;The chromium—Reformatsky reaction: Asymmetric synthesis of the aldol fragment of the cytotoxic epothilons from 3-(2-bromoacyl)-2-oxazolidinonesTetrahedron Lett.381363-1366(1997)DOI: 10.1016/S0040-4039(96)02494-X
In a two step, one pot reaction of 4-benzyl oxazolidinone, 2-bromoacetyl halide, chromium dichloride and a suitable 3-oxo-aldehyde derivative the C1C6Me - fragment of epothilons is available in its correct oxidation state and enantiomeric form. Compared to common methods, the chromium-Reformatsky variation preferentially yields the opposite diastereomers and gives improved chemo- and diastereoselection.
Publications
Gabriel, T.; Wessjohann, L.;The chromium-Reformatsky reaction: anti-selective Evans-type aldol reactions with excellent inverse induction at ambient temperatureTetrahedron Lett.384387-4388(1997)DOI: 10.1016/S0040-4039(97)00952-0
anti-Aldol products are available in a two step, one pot reaction of 4-substituted oxazolidone, 2-bromopropionyl halide, chromium dichloride and an aldehyde. The diastereofacial selection (induction) is opposite to those of boron Evans enolates, i. e. the unusual “non-Evans” anto-aldol products are formed in excellent excess and yield - without base and at room temperature. In contrast to our previous assumptions α-unsubstituted acetyloxazolidones do give the Evans-type β-anti-products preferentially.