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[3 + 2] Annulation Methods Based on Organosilanes

    Our laboratory has pioneered the application of allenylsilanes, propargylsilanes, and allylsilanes as three-carbon units in [3 + 2] annulation routes to a variety of five-membered carbocyclic and heterocyclic systems.  This reaction, sometimes referred to as the "Danheiser Annulation", was selected for the cover of Hassner and Stumer's monograph on "Organic Syntheses Based on Name Reactions and Unnamed Reactions."  

    A number of variants of this [3 + 2] annulation strategy have been developed in our laboratory:

[3 + 2] Cyclopentene Annulation

References:

"TMS-Cyclopentene Annulation: A Regiocontrolled Approach to the Synthesis of Five-Membered Rings", R. L. Danheiser, D. J. Carini, and A. Basak, J. Am. Chem. Soc.1981, 103, 1604.

"Scope and Stereochemical Course of the (Trimethylsilyl)cyclopentene Annulation", R. L. Danheiser, D. J. Carini, D. M. Fink, and A. Basak, Tetrahedron 1983, 39, 935.

"The Reaction of Allenysilanes with a,b-Unsaturated Acylsilanes: New Annulation Approaches to Five and Six-Membered Carbocyclic Compounds", R. L. Danheiser and D. M. Fink, Tetrahedron Lett. 1985, 26, 2513.

"A General [3+2] Annulation: cis-4-Exo-isopropenyl-1,9-dimethyl-8-(trimethylsilyl)bicyclo-[4.3.0]non-8-en-2-one", R. L. Danheiser, D. M. Fink, and Y. -M. Tsai, Organic Syntheses 1988, 66, 8.

[3 + 2] Annulation Route to Azulenes

References:

"A New Synthesis of Substituted Azulenes", D. A. Becker and R. L. Danheiser, J. Am. Chem. Soc. 1989, 111, 389.

[3 + 2] Annulation Route to Five-Membered Oxygen and Nitrogen Heterocycles

References:

"Application of Allenylsilanes in [3 + 2] Annulation Approaches to Five-Membered Oxygen and Nitrogen Heterocycles", R. L. Danheiser, C. A. Kwasigroch, and Y. -M. Tsai, J. Am. Chem. Soc.1985, 107, 7233.

[3 + 2] Annulation Route to Furans

References:

"A New Synthesis of Substituted Furans", R. L. Danheiser, E. J. Stoner, H. Koyama, D. S. Yamashita, and C. A. Klade, J. Am. Chem. Soc.1989, 111, 4407.

[3 + 2] Annulation Route to Isoxazoles

References:

"Application of Allenylsilanes in a Regiocontrolled [3 + 2] Annulation Route to Substituted Isoxazoles", R. L. Danheiser and D. A. Becker, Heterocycles 1987, 25, 277.

[3 + 2] Annulation Methods Based on Allylsilanes and Propargylsilanes

References:

"Five-Membered Ring Annulation via Propargyl- and Allylsilanes", R. L. Danheiser, B. R. Dixon, and R. W. Gleason, J. Org. Chem. 1992, 57, 6094.

"Stereochemical Course of the Allylsilane Based Cyclopentane Annulation", R. L. Danheiser, T. Takahashi, Bila Bertsk, and B. R. Dixon, Tetrahedron Lett. 1993, 34, 3845.

[ Home ] [ [2 + 2 + 2] Cycloaddition Strategies ] [ [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 ]