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Enantioselective Organic Syntheses Using Chiral Transition Metal Complexes, 9 Atropo‐Diastereoselective Ring Opening of Biaryl Thionolactones Using [CpRu{( S , S )‐CHIRAPHOS}] + as a Chiral Auxiliary
Author(s) -
Schenk Wolfdieter A.,
Kümmel Jörg,
Reuther Irene,
Burzlaff Nicolai,
Wuzik Andreas,
Schupp Olaf,
Bringmann Gerhard
Publication year - 1999
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199910)1999:10<1745::aid-ejic1745>3.0.co;2-1
Subject(s) - chemistry , thioether , diastereomer , ruthenium , isomerization , enantioselective synthesis , alkylation , stereochemistry , thiophene , iodide , pyridine , bond cleavage , ring (chemistry) , medicinal chemistry , protonation , organic chemistry , catalysis , ion
The substitution‐labile thiophene complex [CpRu{( S , S )‐CHIRAPHOS}(SC 4 H 4 )]BF 4 ( 2 ) [( S , S )‐CHIRAPHOS = (2 S ,3 S )bis(diphenylphosphanyl)butane], prepared from [CpRu{( S , S )‐CHIRAPHOS}Cl] ( 1 ), thiophene, and AgBF 4 , reacted with the biaryl‐thionolactones 3a–f to give the corresponding S‐coordinated complexes 4a–f in high yields. The structure of 4c , which crystallized as the pure ( S,S,P ) diastereoisomer, was determined by X‐ray crystallography. Coordination of the ruthenium fragment caused an elongation of the C=S bond, a contraction of the C–O bond within the lactone ring and a flattening of that ring. Single hydride transfer with LiBEt 3 H converted 4a–f into the thiolactolate complexes 5a–f in good yields and diastereoselectivities. An X‐ray structure determination of the major isomer of 5a revealed it to be the ( S,S,S,P ) diastereoisomer. Protonation with NH 4 PF 6 converted 5a–f into the corresponding ring‐opened thioaldehyde complexes 6a–f . Alkylation of 5a with methyl iodide resulted in Ru–S cleavage to give the oxothioacetal 7a and [CpRu{( S , S )‐CHIRAPHOS}I] ( 8 ). Full reduction of 4a–f with LiAlH 4 produced the thiolate complexes 9a–f in high yields and 6–74% de. Methylation at sulfur converted 9a–c into the corresponding thioether complexes 10a–c , which were cleaved to 8 and the free methyl thioethers 11a–c without isomerization of the biaryl axis.