Stereoselective Nazarov cyclizations of bridged bicyclic dienones.
[reaction: see text] Bridged bicyclic dienones underwent silyl-directed Nazarov cyclization with generally very high diastereoselectivity. In most cases, a strong preference for cyclization to the product with an exo-disposed cyclopentenone was seen. However, the presence of additional unsaturation in the three-carbon bridge of a bicyclo[3.2.1]octadiene system caused complete reversal in selectivity with exclusive formation of the endo-cyclopentenone. The observed selectivities are believed to result from a combination of steric and electronic effects.
Mazzola
Robert D
RD
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA.
White
Timothy D
TD
Vollmer-Snarr
Heidi R
HR
West
F G
FG
D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
D001643:Bridged Bicyclo Compounds; D003517:Cyclopentanes; D007202:Indicators and Reagents; D007659:Ketones; C007201:cyclopentanone