Pyramidalized olefins: a DFT study of bicyclo[2.1.1]-, -[3.2.1]-, and -[3.2.2]alkenes and their fused derivatives. Two rare examples of pi-facially symmetric pyramidal olefins.
Density functional theory (B3LYP/6-31G) was used to study a large series of bridged polycyclic alkenes based on the bicyclo[2.1.1], -[3.2.1], and -[3.2.2] nuclei. In those compounds with pi-facial dissymmetry, butterfly bending of the strained olefinic bonds was generally predicted. Surprisingly, large pyramidalizations are calculated for the highly strained but pi-facially symmetric tetracyclo[5.1.1.1.(3,5)0(2,6)]dec-2-ene (28, psi = 19.8 degrees ) and tetracyclo[5.2.2.1.(3,5)0(2,6)]dodec-2,8,10-triene (33, psi = 14.4 degrees ). The preference for propano-directed bending in the bicyclo[3.2.1]octenes is about as strong as that for endo bending in norbornenes.
Williams
Richard Vaughan
RV
Department of Chemistry, University of Idaho, P.O. Box 442343, Moscow, Idaho 83844-2343, USA. williams@uidaho.edu
Margetić
Davor
D