Enantioselective formation of quaternary stereocenters using the catalytic intramolecular Stetter reaction

Anwendungen der Katalyse mit N‐heterocyclischen Carbenen in Totalsynthesen

“…[20] Nicolaou et al beschrieben 2009 eine enantioselektive Synthese der monomeren Einheit des Lomaiviticin-Aglykons (30). Insbesondere wurden für Lomaiviticin A gegen zahlreiche Krebszelllinien IC 50 -Werte im Bereich von 0.01 bis 98 mm ermittelt.…”

ChemInform Abstract: Asymmetric N‐Heterocyclic Carbene (NHC) Catalyzed Acyl Anion Reactions

“…23 Contiguous stereocenters could also be generated by using precatalyst 15 with a variety of salicylaldehyde substrates to yield a highly enantioselective and diastereoselective process. The reaction is not limited to salicylaldehyde derived substrates as aliphatic aldehydes also partake in the reaction with high levels of enantio- and diastereoselectivity, the latter being attributed to an intramolecular proton transfer event (eq 4).…”

Carbene Catalysts

“…The scope of this methodology has been expanded to the synthesis of tetrasubstituted stereocenters by inducing the addition of aromatic and aliphatic aldehydes to β,β-disubstituted Michael acceptors [71, 72]. While a series of catalysts were examined, electron-deficient pre-catalyst 75c was found to be the most efficient for this transformation (Table 8).…”

“…The geometry of the Michael acceptor has been shown to play an important role in the intramolecular Stetter reaction [70, 72]. In the case of salicylaldehyde derived substrate 90 , which contains a cis -1,2-disubstituted alkene, no reaction occurs under standard reaction conditions.…”