Abstract
The use of pseudo enantiomers is a well-known method of achieving products of complementary stereochemistry. Only rarely can different enantiomers of a product be accessed without modulation of the catalyst. Recently, a system was reported wherein two different enantiomers of spirocycles were obtained by a cascade reaction of unsaturated pyrrolin-4-ones with mercaptoacetaldehyde catalyzed by a single optimized cinchona alkaloid squaramide-derived organocatalyst. It was originally proposed that the E -/ Z -geometry of the unsaturated pyrrolin-4-one dictated the stereochemistry of the spirocycle product, but this was not investigated further. In the present work, we have investigated the nature of a pseudo-enantiomeric organocatalyst conformation applying density functional theory calculations for investigating the transition states for the reaction. Furthermore, the influence of the double-bond geometry of the pyrrolin-4-one has been studied beyond what is possible to test experimentally. The results provide a greater understanding for this class of reactions that may be applicable in future methodology development.
| Original language | English |
|---|---|
| Journal | Chemistry: A European Journal |
| Volume | 26 |
| Issue | 67 |
| Pages (from-to) | 15727-15732 |
| Number of pages | 6 |
| ISSN | 0947-6539 |
| DOIs | |
| Publication status | Published - Dec 2020 |
Keywords
- Aldol reaction
- Michael addition
- cinchona alkaloids
- density functional theory
- organocatalysis