A [4+4] annulation strategy for the synthesis of eight-membered carbocycles based on intramolecular cycloadditions of conjugated enynes

作者：Robinson Julia M; Tlais Sami F; Fong Jennie; Danheiser Rick L^*

来源：Tetrahedron, 2011, 67(51): 9890-9898.

DOI：10.1016/j.tet.2011.09.031

• Conjugated enynes
• Eight-membered rings
• Cycloaddition
• Electrocyclic ring opening
• Cyclooctatrienones

A [4+4] annulation strategy for the synthesis of eight-membered carbocycles is reported that proceeds via a cascade involving two pericyclic processes. In the first step, the [4+2] cycloaddition of a conjugated enyne with an electron-deficient cyclobutene generates a strained six-membered cyclic allene that isomerizes to the corresponding 1,3-cyclohexadiene. In the second step, this bicyclo[4.2.0]octa-2,4-diene intermediate undergoes thermal or acid-promoted 6-electron electrocyclic ring opening to furnish a 2,4,6-cyclooctatrienone. The latter transformation represents the first example of the promotion of 6-electron electrocyclic ring opening reactions by acid.

• 出版日期2011-12-23