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Efficient Palladium‐Catalyzed Substitution in Enantiomerically Pure Allyl Carbonates – A Stereodivergent Access to β‐Aryl‐Substituted γ‐Lactones and γ‐Hydroxy Amides
Author(s) -
Braun Manfred,
Unger Claudia,
Opdenbusch Kersten
Publication year - 1998
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199811)1998:11<2389::aid-ejoc2389>3.0.co;2-t
Subject(s) - chemistry , palladium , allylic rearrangement , diastereomer , dimethyl malonate , malonate , aryl , enantioselective synthesis , catalysis , reagent , stereochemistry , medicinal chemistry , substitution reaction , organic chemistry , alkyl
Allyl carbonates ( Z )‐ 8 and ( E )‐ 9 are available from the addition of the chiral alkenyllithium reagent 5b to aromatic aldehydes 6 . When sujected to a palladium‐catalyzed substitution by sodium malonate, ( Z )‐carbonates 8 give diesters 10 and 11 , whereas ( E )‐carbonate 9 predominantly leads to the diastereomeric product 12 . The latter is converted into ( S )‐γ‐butyrolactone 13 in a three step sequence. When the same protocol is applied to the isomeric diesters 10 and 11 , ( R )‐lactones 13 result. A rationale for the stereochemical outcome of the allylic substitutions in the carbonates 10‐12 is offered, based on π‐σ‐π interconversions of the palladium complexes 20‐23 .