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Synthesis of Enantiomerically Pure (−)‐Wine Lactone Based on a Palladium‐Catalyzed Enantioselective Allylic Substitution
Author(s) -
Bergner Eike J.,
Helmchen Günter
Publication year - 2000
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(200002)2000:3<419::aid-ejoc419>3.0.co;2-n
Subject(s) - enantioselective synthesis , chemistry , palladium , allylic rearrangement , substitution (logic) , wine , catalysis , lactone , substitution reaction , organic chemistry , stereochemistry , food science , computer science , programming language
The first enantioselective synthesis of enantiomerically pure (−)‐wine lactone, (−)‐ 1a , a fragrance constituent of various white wines, and its epimer (+)‐ 1b , was carried out. The key steps are allylic substitution of (±)‐2‐cyclohexen‐1‐yl acetate ( 2 ) with dimethylmalonate using palladium complexes of phosphanyldihydrooxazol L1 or of the phosphanylcarboxylic acid L2 as catalyst, subsequent decarboxylation, iodolactonization and elimination, furnishing enantiomerically pure bicyclic lactone (+)‐ 7 in 47% overall yield. The diastereoselective introduction of methyl groups by S N 2′‐type substitution with an organocopper compound and by enolate alkylation gave lactone (−)‐ 1a in 43% overall yield from (+)‐ 7 .