Synthesis of Seven-Membered Cross-Conjugated Cyclic Trienes by 8π Electrocyclic Reaction
Ranmaru Kato, Hiroki Saito, Shoko Uda, Daisuke Domon, Kazutada Ikeuchi, Takahiro Suzuki, Keiji Tanino
Abstract
A method for the synthesis of 3-methylene-1,4-cycloheptadiene derivatives via an 8π electrocyclization reaction was developed. The triene substrate bearing a phosphate or carbamate group was prepared from γ,δ-unsaturated esters and α,β-unsaturated aldehydes in four steps. Upon treatment with NaHMDS or KHMDS, the substrate formed a heptatrienyl anion, which underwent electrocyclization and subsequent β-elimination of the leaving group. The product could be converted into a tropylium salt in two steps.
Topics & Concepts
ChemistryCarbamateSubstrate (aquarium)Conjugated systemMethyleneSalt (chemistry)Medicinal chemistryIonOrganic chemistryOceanographyPolymerGeologySynthetic Organic Chemistry MethodsAsymmetric Synthesis and CatalysisAdvanced Synthetic Organic Chemistry