Synthesis of Seven-Membered Cross-Conjugated Cyclic Trienes by 8π Electrocyclic Reaction

• DOI: 10.1021/acs.orglett.1c03383
• Publication Date: 2021-10-29T13:28:45Z
• Authors: Ranmaru Kato; Hiroki Saito; Shoko Uda; Daisuke Domon; Kazutada Ikeuchi; Takahiro Suzuki; Keiji Tanino
• Keywords: 01 natural sciences; 0104 chemical sciences

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.