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Ruthenium–Lewis Acid Catalyzed Asymmetric Diels–Alder Reactions between Dienes and α,β‐Unsaturated Ketones
Author(s) -
Rickerby Jenny,
Vallet Martial,
Bernardinelli Gerald,
Viton Florian,
Kündig E. Peter
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600851
Subject(s) - ruthenium , alder , catalysis , lewis acids and bases , diels–alder reaction , chemistry , organic chemistry , medicinal chemistry , biology , botany
The complex [Ru(Cp)( R , R ‐BIPHOP‐F)(acetone)][SbF 6 ], ( R , R )‐ 1 a , was used as catalyst for asymmetric Diels–Alder reactions between dienes (cyclopentadiene, methylcyclopentadiene, isoprene, 2,3‐dimethylbutadiene) and α,β‐unsaturated ketones (methyl vinyl ketone (MVK), ethyl vinyl ketone, divinyl ketone, α‐bromovinyl methyl ketone and α‐chlorovinyl methyl ketone). The cycloaddition products were obtained in yields of 50–90 % and with enantioselectivities up to 96 % ee . Ethyl vinyl ketone, divinyl ketone and the halogenated vinyl ketones worked best and their reactions with acyclic dienes consistently provided products with >90 % ee . α‐Chlorovinyl methyl ketone performed better than α‐bromovinyl methyl ketone. The reaction also provided a [4.3.1]bicyclic ring system in 95 % ee through an intramolecular cycloaddition reaction. Crystal structure determinations of [Ru(Cp)(( S , S )‐BIPHOP‐F)(mvk)][SbF 6 ], ( S , S )‐ 1 b , and [Ru(Cp)(( R , R )‐Me 4 BIPHOP‐F)(acrolein)][SbF 6 ], ( R , R )‐ 2 b , provided the basis for a rationalization of the asymmetric induction.