Influence des ultrasons sur la diastéréosélectivité. Synthèse d'imidazolidine-4-one chirales
摘要:
A three-step synthesis of imidazolidine-4-one has been realized. Sodium dithionite was a very efficient reagent for the last step, the reduction of a ketone. The reaction is slow under the normal conditions of heating and its diastereoselectivity is poor. Under the influence of ultrasound, the selectivity and the yield are very good. The use of sodium dithionite makes it possible to work in water and to avoid the use of hydrides.
5-Substituted (5S)-imidazolidin-4-ones as effective chiral auxiliary for hydrogenation of ?-keto amides
摘要:
The title chiral auxiliary was used for asymmetric catalytic hydrogenation of amides derived from phenylglyoxylic acid to give mandelamides with high diastereoselectivity (diastereoisomeric excess, d. e. up to 96%).