Expanding the scope of enantioselective ferroPHANE-promoted [3+2] annulations with alpha,beta-unsaturated ketones.
The planar chiral 2-phospha[3]ferrocenophane I has been shown to be the first efficient nucleophilic organocatalyst for the enantioselective synthesis of cyclopentenylphosphonates, through [3+2] cyclizations between diethyl allenylphosphonate and alpha,beta-unsaturated ketones. The same catalyst has also been applied to the highly enantioselective [3+2] cyclizations of allenic esters with dibenzylideneacetone and analogous bis-enones, leading to functionalised cyclopentenes with either monocyclic or spirocyclic structures (ee 84-95 %). It has been shown that the residual enone functions in the resulting cyclopentenes can be involved in subsequent cyclization steps to afford unprecedented C(2)-symmetric bis-cyclopentenylketones. In order to provide insight into the behaviour of FerroPHANE I as a chiral catalyst in [3+2] cyclisations, the energetically most favoured isomers of the key phosphine-allene adduct have been calculated by DFT methods. Factors likely to control the chiral induction process are highlighted.
Pinto
Nathalie
N
Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles-CNRS UPR 2301, 1, av. de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
Neel
Mathilde
M
Panossian
Armen
A
Retailleau
Pascal
P
Frison
Gilles
G
Voituriez
Arnaud
A
Marinetti
Angela
A
D002384:Catalysis; D018360:Crystallography, X-Ray; D003500:Cyclization; D005296:Ferrous Compounds / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008968:Molecular Conformation; D010720:Phosphines / Q000737:chemistry; D010721:Phosphinic Acids / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
D005296:Ferrous Compounds; D007659:Ketones; D010720:Phosphines; D010721:Phosphinic Acids; C044646:phosphine