Efficient and stereoselective synthesis of bicyclo[3.2.1]octan-8-ones: synthesis and palladium-catalyzed isomerization of functionalized 2-vinyl-2,3,3a,4,5,6-hexahydro-2,3-benzofurans.
A new C,O-cyclodialkylation of dilithiated cyclic beta-keto esters and beta-keto sulfones with 1,4-dibromo-2-butene is reported which results in regio- and diastereoselective formation of 2-vinyl-2,3,3a,4,5,6-hexahydro-2,3-benzofurans. The products could be efficiently transformed into functionalized bicyclo[3.2.1]octan-8-ones by a palladium-catalyzed rearrangement reaction. In case of sulfone derivatives, this rearrangement proceeds with high stereospecifity to give exclusively the endo-configured diastereomers. The bicyclo[3.2.1]octane skeleton is present in a large number of pharmacologically important natural products.
Langer
Peter
P
Institut für Organische Chemie der Georg-August-Universität Göttingen Tammannstrasse 2, 37077 Göttingen, Germany. planger@uni-goettingen.de
Holtz
Edith
E
Saleh
Nehad N R
NN
D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D002626:Chemistry, Pharmaceutical; D007659:Ketones / Q000138:chemical synthesis / Q000737:chemistry; D009795:Octanes / Q000138:chemical synthesis* / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
D001572:Benzofurans; D019086:Bridged Bicyclo Compounds, Heterocyclic; D007659:Ketones; D009795:Octanes; D010165:Palladium