Supramolecular Hydrogen-Bonding Tautomeric Sulfonamido–Phosphinamides: A Perfect P-Chirogenic Memory
✍ Scribed by Frederic W. Patureau; Maxime A. Siegler; Anthony L. Spek; Albertus J. Sandee; Sylvain Jugé; Sarwar Aziz; Albrecht Berkessel; Joost N. H. Reek
- Book ID
- 102830596
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 790 KB
- Volume
- 2012
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
P‐chirogenic, supramolecular hydrogen‐bonding C~1~‐symmetrical sulfonamido–phosphinamides (METAMORPhos) have been successfully prepared. They were all found to possess a characteristic prototropic equilibrium between the P^III^ and the P^V^ tautomers that is slow on the NMR spectroscopic timescale. Despite the dynamic and reversible protonation of the P centre, the P‐chirogenic information was found to be retained in the tautomerization process, even in a protic solvent environment. Several strategies to access the corresponding enantiopure compounds were investigated, such as diastereoselective crystallization, or enantioselective synthesis. It was possible to resolve such a class of chiral ligands with up to 99 % ee, and apply them in the Rh‐catalyzed asymmetric hydrogenation of alkenes. These ligands are interesting new building blocks in the area of acid/base‐type noninnocent ligand catalysis.