Structure of Octamethylene‐Bridged Derivatives of 1,3‐Cyclohexadiene and Bicyclo[3.1.0]hexene

Abstract

AbstractSynthesis and photochemical generation of the octamethylene‐bridged 1,3‐cyclohexadiene and bicyclo[3.1.0]hexene derivatives 1 and 2, which are to be classified as anti‐Bredt olefins, are reported. out Orientation of the octamethylene bridge at the sp3‐hybridized bridgehead atom of 1 generates strain effects while in orientation of the bridge in 2 does not give rise to deformations of the bicyclo[3.1.0]hex‐2‐ene subunit. X‐ray analyses indicate a twisted double bond (12.2 and 15.0°) at the bridgehead atom of 1 and a deformation of the six‐membered ring from an ideal boat conformation. In contrast, the five‐membered ring of compound 2 is planar. The folding angle between the five‐ and the three‐membered ring is 111.8(2)°. The olefinic carbon atoms of 1 are slightly pyramidalized.