Cycloadditions Based on Highly Unsaturated, Conjugated Molecules

The general goal of our work in this area is the design of cycloaddition processes which, like cycloaromatizations, involve highly unsaturated conjugated molecules and proceed via strained and/or high energy intermediates to produce new aromatic and dihydroaromatic rings. We have shown that the intramolecular [4+2] cycloaddition of conjugated enynes with alkynes and alkenes provides a powerful method for the synthesis of aromatic and dihydroaromatic compounds. In recent studies, we have also developed the first heterocyclic variant of the enyne cycloaddition.

References:

"Intramolecular [4+2] Cycloaddition Reactions of Conjugated Enynes", R. L. Danheiser, A. E. Gould, R. Fernandez de la Pradilla, and A. L. Helgason, J. Org. Chem. 1994, 59, 5514.

"Intramolecular [4+2] Cycloaddition Reactions of Conjugated Ynones. Formation of Polycyclic Furans via the Generation and Rearrangement of Strained Heterocyclic Allenes", M. S. B. Wills and R. L. Danheiser, J. Am. Chem. Soc. 1998, 120, 9378.

"Synthesis of Highly Substituted Indolines and Indoles via Intramolecular [4 + 2] Cycloaddition of Ynamides and Conjugated Enynes ", J. R. Dunetz and R. L. Danheiser, J. Am. Chem. Soc. 2005, 127, 5776 .

"Intramolecular [4+2] Cycloadditions of Benzynes with Conjugated Enynes, Arenynes, and Dienes",  M. E. Hayes, H. Shinokubo, and R. L. Danheiser, Org. Lett. 2005 , 7, 3917.

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