Massive parallel catalyst screening: toward asymmetric MCRs.
[reaction: see text]. Hundreds of Lewis acid/ligand combinations have been screened for stereochemical induction in the Passerini multicomponent reaction. The combination of titan tetraisopropylate and (4S,5S)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane was found to give enantiomeric excesses between 32% and 42% in several examples. The absolute stereo induction of one example was determined chemically and by means of X-ray crystallography. This comprises the first asymmetric Passerini reaction and the first example of a stereochemical induction in an isocyanide based multicomponent reaction by a chiral Lewis acid.
Morphochem AG, Gmunderstr.37-37a, 81379 München, Germany.
Ulrike
U
Kusebauch
Barbara
B
Beck
Kim
K
Messer
Eberhardt
E
Herdtweck
Alexander
A
Dömling