✦ LIBER ✦
Enantioselective sequential transformations by use of metal complexes: Tandem-Knoevenagel-hetero-Diels–Alder reactions with new chiral Lewis acids
✍ Scribed by Dr. Lutz F. Tietze; Peter Saling
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 210 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0899-0042
No coin nor oath required. For personal study only.
✦ Synopsis
Enantioselective reaction of the aldehydes la-g and the 1,3-dicarbonyl compound 2 in the presence of the chiral Lewis acid 5, derived from diacetone glucose, leads in a sequential transformation consisting of a Knoevenagel condensation and an intramolecular Diels Alder reaction to the cycloadducts 4a-g with an ee value up to 88%. The selectivity is strongly dependent upon the temperature and solvent giving best results at room temperature in isodurene; in agreement with the principle of isoinversion, the ee values decrease at lower and higher temperatures. o 19% Wiley-Liss. Inc.