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Cycloadditions and Annulation Methods Based on Vinylketenes

Our laboratory has pioneered the application of vinylketenes as four-carbon building blocks for the construction of four-, five-, six-, and eight-membered carbocyclic and heterocyclic compounds. In 1980 we reported the first synthesis of (trimethylsilyl) vinylketene, and in subsequent research we have developed several general methods for the preparation of (trialkylsilyl) vinylketenes ("TAS-vinylketenes"). We have shown that these remarkably stable ketenes are versatile, multi-functional synthetic building blocks which engage in a number of useful cycloaddition and annulation reactions leading to four-, five-, six-, and eight-membered carbocyclic and heterocyclic compounds.

Benzannulation Strategies for the Synthesis of Highly-Substituted Aromatic Compounds

References:

See also applications in the total synthesis of Mycophenolic acid, Maesanin, Dihydrotanshinone I, Tanishone I and IIA, Aegyptinones A and B, Salvilenone, Bergapten, Neocryptotanshinone, Cryptotanishone, Royleanone, and Ascochlorin.

Diels-Alder Reactions of TAS-Vinylketenes

References:

 "Trimethylsilylvinylketene: A Stable Vinylketene and Reactive Enophile in [4+2] cycloadditions", R. L. Danheiser and H. Sard, J. Org. Chem. 1980, 45, 4810.

"(Trialkylsilyl)vinylketenes: Synthesis and Application as Diene Components in Diels-Alder Cycloadditions", J. L. Loebach, D. M. Bennett, and R. L. Danheiser, J. Org. Chem. 1998, 63, 8380.

"Hetero [4+2] Cycloadditions of (Trialkylsilyl)vinylketenes. Synthesis of a,b-Unsaturated d-Valerolactones and -Lactams", D. M. Bennett, I. Okamoto, and R. L. Danheiser, Org. Lett. 1999, 1, 641.

[4+4] Annulation for the Synthesis of Eight-membered Rings

References:

"A [4+4] Annulation Approach to Eight-Membered Carbocyclic Compounds", R. L. Danheiser, S. K. Gee, and H. Sard, J. Am. Chem. Soc. 1982, 104, 7670.

[4+1] Annulation Route to Cyclopentenones and Indanones

References:

"The Reaction of (Trialkylsilyl)vinylketenes with Carbenoid Reagents: A New [4+1] Annulation Route to Cyclopentenones",  J. L. Loebach, D. M. Bennett and R. L. Danheiser, J. Am. Chem. Soc. 1998, 120, 9690.

"Synthesis of 2-Indanones via [4 + 1] Annulation Reactions of (Trialkylsilyl)arylketenes", A. M. Dalton, Y. Zhang, C. P. Davie and R. L. Danheiser, Org. Lett. 2002, 4, 2465.

"Stereoselective Synthesis of Highly Substituted Cyclopentenones through [4 + 1] Annulations of Trialkylsilyl Vinyl Ketenes with ±-Benzotriazolyl Organolithium Compounds",  C. P. Davie and R. L. Danheiser, Angew. Chem. Int. Ed. 2005 , 44 , 5867.

Cyclohexenol Annulation Strategy

References:

"Cyclohexenol Annulation via the Alkoxy-accelerated Rearrangement of Vinylcyclobutanes", R. L. Danheiser, C. Martinez-Davila, and H. Sard, Tetrahedron 1981, 37, 3943.

[ Home ] [ [3 + 2] Annulations of Organosilanes ] [ Vinylcyclopropane Rearrangements ] [ Cycloadditions and Annulations of Vinylketenes ] [ Highly Unsaturated, Conjugated Molecules ] [ [4 + 2] Cycloadditions of Imine Derivatives ] [ Ketene [2 + 2] Cycloadditions ] [ Acylsilanes ] [ B-Lactones ] [ Cyclopropylboranes ] [ Allenylsilanes and Homopropargylic Alcohols ] [ Cationic Cyclizations ] [ Synthesis of Azulenes ] [ Miscellaneous Synthetic Methods ]